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2015 Technical Documentation

Component ID: #ti586816477

Introduction:

The U.S. Census Bureau has been releasing county-to-county and county/minor civil division (MCD)-to-county/MCD migration flow estimates based on the American Community Survey (ACS) since 2012. [1] The first table package used data collected from 2005 through 2009 that composed the first ACS 5-year dataset.[2] For sequential 5-year ACS datasets, tables were crossed by selected characteristics. The 2008-2012 release was the first time flows from Puerto Rico municipios to U.S. counties were included. Flows between metropolitan statistical areas (MSAs) were introduced with the 2009-2013 dataset.[3] In addition, the county-to-county flows going back to 2006-2010 dataset are available through the Census Flows Mapper.[4] As of 2016, all ACS migration flows data for counties, MCDs, and MSAs were made available in the Census application programming interface (API) through the Census Developers site.[5]


Collection Years

Geographic Summary Levels

Characteristics

2005-2009

County, MCD*

None

2006-2010

County, MCD*

Age, sex, race, or Hispanic origin

2007-2011

County, MCD*

Educational attainment, household income, or individual income

2008-2012

County, MCD*

Employment status, work status, or occupation

2009-2013

MSA, county, MCD*

Ability to speak English, place of birth, or years in the United States (or Puerto Rico)

2010-2014

MSA, county, MCD*

Relationship to householder, household type, or housing tenure

2011-2015

MSA, county, MCD*

Age, sex, race, or Hispanic origin

*Data at the MCD level are only available for the strong-MCD states of Connecticut, Maine, Massachusetts, Michigan, Minnesota, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, and Wisconsin.



The 2011-2015 Release:

The current release uses the first non-overlapping 5-year dataset since ACS migration flow tables crossed by characteristics were released. Therefore, the same demographic characteristics used for the 2006-2010 dataset are repeated for the current release: age, sex, race, or Hispanic origin.

The universe for all the characteristics is the population 1 year and over. Age is broken down into the following fifteen categories: 1 to 4 years, 5 to 17 years, 18 to 19 years, 20 to 24 years, 25 to 29 years, 30 to 34 years, 35 to 39 years, 40 to 44 years, 45 to 49 years, 50 to 54 years, 55 to 59 years, 60 to 64 years, 65 to 69 years, 70 to 74 years, and 75 years and over.

The four race categories consist of white alone, black or African American alone, Asian alone, and other race alone or two or more races. The three Hispanic origin categories are white alone, not Hispanic or Latino; not white alone, not Hispanic or Latino; and Hispanic or Latino.

Disclosure Avoidance:

Due to the amount of data released through standard 5-year ACS data products as well as the public use microdata samples (PUMS), and because sequential annual 5-year estimates contain overlapping samples; the Census Bureau must be vigilant in order to protect confidentiality of the respondents. Any data products that the Census Bureau releases must be reviewed and approved by the Disclosure Review Board based on disclosure avoidance rules to assure confidentiality of the respondents is protected according to Section 9 of Title 13 of the United States Code. It states “Neither the Secretary, nor any other officer or employee of the Department of Commerce or bureau or agency thereof, or local government census liaison may…make any publication whereby the data furnished by any particular establishment or individual under this title can be identified…”[6]

Record swapping, done to protect confidentiality, is applied to the ACS dataset used to create the flow files.[7] The additional disclosure avoidance measure of suppressing flows with small numbers of cases is applied for any flows with characteristics.[8] Flow counts and mover counts without characteristics, however, are not suppressed. The exact disclosure measures are determined by the Disclosure Review Board before each future product is released.[9]

Complementary suppression is applied to the MSA flows by characteristics so that suppressed county flows cannot be derived. If one and only one county-to-county flow of all the flows that aggregate up to a MSA-to-MSA flow is suppressed, then the MSA flow is suppressed. This can include small flows along with larger flows. If a MSA-to-MSA flow is suppressed for a particular characteristic, some information about the flow can be obtained from the MSA-to-MSA flow table without characteristics along with the county-to-county flows by that characteristic within each MSA that are not suppressed.  In addition to the MSA flows, complementary suppression is applied to county/MCD-to-county/MCD flows.

Since some flows are suppressed, summary statistics for each county, MCD, or MSA (e.g., number of nonmovers, movers to a different state) are included in the flow files. Tables crossed by selected characteristics are published annually as part of the ACS standard data products available through American FactFinder (AFF) for both current residence and residence 1 year ago geography. The selected characteristics do not cover the same characteristics used in this release. [10] The Census Bureau applies separate disclosure avoidance rules to these tables containing residence 1 year ago estimates. The universe for each table must have at least 50 unweighted cases for the Census Bureau to publish the table. The same rules are applied to the county-to-county, county/MCD-to-county/MCD, and MSA-to-MSA files. If there is not a sufficient number of cases, the summary statistics for county, MCD, or MSA of residence 1 year ago by characteristics are not shown.


Blank Values:


There are blank cells within the tables. An estimate may be blank for the following reasons.


  1. The estimate is out of scope for the ACS sample – such as supplemental statistics for world regions.
  2. The estimate does not exist – such as movers to a different county in the same state for the District of Columbia.
  3. The supplemental statistics for county of residence 1 year ago or MCD of residence 1 year ago were suppressed due to disclosure avoidance (characteristic files only).


Besides blank estimates, flows with no records in the database and suppressed flows crossed by characteristics are not included in the files. The flows with no records are considered zero count estimates. The margins of error (MOE) for these zero count estimates cannot be calculated using the standard replicate variance formula.[11] For published ACS data products, the MOE for a zero count estimate is calculated using a different method. The standard errors for the zero count estimates are calculated by taking the square root of the product of the 90th percentile k-value and the average weight for the state of residence. Estimates for previous residence use the U.S. average weight. The standard error is then multiplied by 1.645 in order to get the 90 percent MOE.[12] Before the 2012 ACS, only a single k-value was used. The methodology was changed to account for more nuanced k-values. This resulted in 6 different k-values for 5-year ACS. They are assigned based upon the total population of an area. For certain geographies, the total population is the official population estimate. If there is no official population estimate available, then the total population may be found in table B01003 through American FactFinder.


Population Thresholds

k-value

Margin of Error

Using Minimum Average Weight (7)

Using Maximum Average Weight (16)

Less than 5,000

4

9

13

5,000 to less than 10,000

8

12

19

10,000 to less than 20,000

10

14

21

20,000 to less than 30,000

14

16

25

30,000 to less than 50,000

18

18

28

Greater than or equal to 50,000

22

20

31


The average weights are calculated for each state of current residence and the k-value for the county of current residence is used. All estimates for residence 1 year ago and current residence estimates for metro areas that cross state lines should use the average weight for the United States.


State of Current Residence

Average Weight


State of Current Residence

Average Weight


State of Current Residence

Average Weight

Alabama

12


Maryland

13


South Carolina

14

Alaska

7


Massachusetts

13


South Dakota

8

Arizona

14


Michigan

9


Tennessee

13

Arkansas

12


Minnesota

7


Texas

15

California

13


Mississippi

14


Utah

11









Colorado

12


Missouri

11


Vermont

7

Connecticut

13


Montana

9


Virginia

13

Delaware

12


Nebraska

8


Washington

13

Dist. of Columbia

13


Nevada

14


West Virginia

11

Florida

16


New Hampshire

11


Wisconsin

7









Georgia

15


New Jersey

13


Wyoming

12

Hawaii

11


New Mexico

12


Puerto Rico

16

Idaho

12


New York

12




Illinois

11


North Carolina

13


United States

12

Indiana

12


North Dakota

7












Iowa

8


Ohio

11




Kansas

9


Oklahoma

8




Kentucky

12


Oregon

13




Louisiana

13


Pennsylvania

9




Maine

8


Rhode Island

14







Coverage and Group Quarters Population:


The American Community Survey covers the entire population residing in the United States and Puerto Rico, both in housing units and group quarters facilities. Each year, independent housing unit address samples are selected for each county equivalent in the United States and Puerto Rico. Samples of group quarters facilities and persons in group quarters are done at the state level, including Puerto Rico and the District of Columbia. In order to provide a better representation of group quarters estimates over smaller areas, whole person imputation into not-in-sample group quarters facility was started with the 2011 ACS, including the 2007-2011 ACS 5-year estimates.[13] To better preserve the relationship between current and previous residence for these imputed cases, a recipient’s county of residence 1 year ago is changed to the current county of residence if the donor moved within the same county; otherwise, the donor’s county of residence 1 year ago is used for the imputation.


The group quarters population includes people living in correctional institutions, juvenile detention facilities, nursing homes, other long-term care facilities, college dormitories, military facilities, and other noninstitutionalized facilities. An occasional anomaly in the number of movers between a county pair can occur due to whole person group quarters imputation and higher rates of inter-county migration for people in group quarters compared to the general public. The 2011-2015 ACS inter-county mover rates for group quarters are shown in the table below. The estimated group quarters population for a county can be found in detailed table B26001 on American FactFinder.



Population 1 year and over

Percent movers between counties within the United States

Percent movers from abroad

Estimate

MOE

Percent

MOE

Percent

MOE

Total:

312,784,059

+/-14,581

5.5

+/-0.1

0.6

+/-0.1

     Group Quarters:

8,052,552

+/- 349

29.9

+/-0.1

1.8

+/-0.1

          Adult correctional facilities

2,239,400

+/- 538

32.3

+/-0.3

1.0

+/-0.1

          Nursing facilities/skilled facilities

1,498,277

+/- 27

8.3

+/-0.1

0.0

+/-0.1

          College/university housing

2,620,428

+/- 27

41.5

+/-0.2

3.2

+/-0.1

Source: U.S. Census Bureau, 2011-2015 American Community Survey, Subject Table S2601B





Application Programming Interface (API):


In 2016, all ACS migration flows data for counties, MCDs, and MSAs were made available in the Census API through the Census Developers site.[14] The API files contain the same estimates that were previously released in table form and Census Flows Mapper, but the data are provided in a different layout to allow developers to design web and mobile apps that include Census Bureau statistics. See the API website for more information.


Format of the Files:


There are separate text and Excel files for flows between counties, flows between metropolitan statistical areas (MSAs), and flows between minor civil divisions (MCDs) in some selected states. In several states, minor civil divisions are county subdivisions that are the primary governmental or administrative divisions of a county. In 12 states, the MCD governments serve as general-purpose local governments similar to incorporated municipalities.[15] In some of these states, county governments are limited or non-existent; therefore, MCDs are used as the main substate aggregate unit rather than counties. These 12 states are assigned MCD codes for residence 1 year ago during the geocoding process for ACS.



County-to-County Flow Files with No Characteristics


The county-to-county flow files are provided in two formats. There is one fixed field length national text file sorted by current residence geography. There is also an Excel file (.xlsx) containing a worksheet for each state of current residence, including Puerto Rico and the District of Columbia, and another Excel file containing a worksheet for each state of residence 1 year ago.


Besides the county of current residence, county of residence 1 year ago, and the number of movers between the two, the files also contain additional geographical mobility estimates for each county, along with the margin of error (MOE) at the 90 percent confidence level. (For further information about the geographies used for the files see Appendix A.)


The layout of the text file is as follows:

Field Description

Field Position

Current Residence FIPS State Code

1-3

Current Residence FIPS County Code

4-6

Residence 1 Year Ago FIPS State Code/U.S. Island Areas Code/Foreign Region Code

7-9

Residence 1 Year Ago FIPS County Code

10-12

Current Residence State Name

14-43

Current Residence County Name

44-78

Population 1 Year and Over Current County – Estimate

80-87

Population 1 Year and Over Current County – MOE

89-96

Nonmovers Current County – Estimate

98-104

Nonmovers Current County – MOE

106-112

Movers within the United States for Current County or within Puerto Rico for Current Municipio – Estimate

114-120

Movers within the United States for Current County or within Puerto Rico for Current Municipio – MOE

122-128

Movers within the Same County for Current County – Estimates

130-136

Movers within the Same County for Current County – MOE

138-144

Movers from a Different County in the Same State for Current County – Estimate

146-152

Movers from a Different County in the Same State for Current County – MOE

154-160

Movers from a Different State for Current County – Estimate

162-168

Movers from a Different State for Current County – MOE

170-176

Movers from Abroad – Estimate

178-184

Movers from Abroad – MOE

186-192

Residence 1 Year Ago State Name/U.S. Island Areas/Foreign Region

194-223

Residence 1 Year Ago County Name

224-258

Population That Lived in County 1 Year Ago – Estimate

260-267

Population That Lived in County 1 Year Ago – MOE

269-276

Nonmovers County of Residence 1 Year Ago – Estimate

278-284

Nonmovers County of Residence 1 Year Ago– MOE

286-292

Movers within the United States for County of Residence 1 Year Ago or within Puerto Rico for Municipio of Residence 1 Year Ago – Estimate

294-300

Movers within the United States for County of Residence 1 Year Ago or within Puerto Rico for Municipio of Residence 1 Year Ago – MOE

302-308

Movers within the Same County for County of Residence 1 Year Ago – Estimates

310-316

Movers within the Same County for County of Residence 1 Year Ago – MOE

318-324

Movers to a Different County in the Same State for County of Residence 1 Year Ago – Estimate

326-332

Movers to a Different County in the Same State for County of Residence 1 Year Ago – MOE

334-340

Movers to a Different State for County of Residence 1 Year Ago – Estimate

342-348

Movers to a Different State for County of Residence 1 Year Ago – MOE

350-356

Movers to Puerto Rico – Estimate

358-364

Movers to Puerto Rico – MOE

366-372

Movers within Flow – Estimate

374-380

Movers within Flow – MOE

382-388



County-to-County Net and Gross Migration Files (No Characteristics)


There are two files, text and Excel, that contains flow, counterflow, net migration, and gross migration for all county pairs (Geography A and Geography B). The Excel file has a worksheet for each state. Both files are sorted by Geography A. The flow shows the inmigration from Geography B to Geography A. The counterflow shows the outmigration from Geography A to Geography B. The net migration is the flow minus the counterflow, and the gross migration is the flow plus the counterflow.


The layout for the text file is as follows:

Field Description

Field Position

State/U.S. Island Area/Foreign Region Code of Geography A (state code based on FIPS code)

1-3

FIPS County Code of Geography A

4-6

State/U.S. Island Area/Foreign Region of Geography B (state code based on FIPS code)

7-9

FIPS County Code of Geography B

10-12

State/U.S. Island Area/Foreign Region Name of Geography A

14-43

County Name of Geography A

44-78

State/U.S. Island Area/Foreign Region Name of Geography B

80-109

County Name of Geography B

110-144

Flow from Geography B to Geography A – Estimate

146-153

Flow from Geography B to Geography A – MOE

155-162

Counterflow from Geography A to Geography B – Estimate

164-171

Counterflow from Geography A to Geography B – MOE

173-180

Net Migration from Geography B to Geography A – Estimate

182-189

Net Migration from Geography B to Geography A – MOE

191-198

Gross Migration between Geography A and Geography B – Estimate

200-207

Gross Migration between Geography A and Geography B – MOE

209-216



County-to-County Flow Files by Characteristics


There is a set of county-to-county files, text and Excel, for each of the three characteristics. The county-to-county characteristic flow files have the same fields as the county-to-county flow files with the additional field for characteristic code in positions 14-15. The field contains relationship to householder code, household type code, or housing tenure code depending upon the file.


The layout of the text file is as follows:

Field Description

Field Position

Current Residence FIPS State Code

1-3

Current Residence FIPS County Code

4-6

Residence 1 Year Ago FIPS State Code/U.S. Island Areas Code/Foreign Region Code

7-9

Residence 1 Year Ago FIPS County Code

10-12

Characteristic Code


Age Code:

            01 = 1 to 4 years

            02 = 5 to 17 years

            03 = 18 to 19 years

            04 = 20 to 24 years

            05 = 25 to 29 years

            06 = 30 to 34 years

            07 = 35 to 39 years

            08 = 40 to 44 years

            09 = 45 to 49 years

            10 = 50 to 54 years

            11 = 55 to 59 years

            12 = 60 to 64 years

            13 = 65 to 69 years

            14 = 70 to 74 years

            15 = 75 years and over


Sex Code:

            01 = Male

            02 = Female


Race Code:

            01 = White alone

            02 = Black or African American alone

            03 = Asian alone

            04 = Other race alone or Two or more races


Hispanic or Latino Origin:

            01 = White alone, not Hispanic or Latino

            02 = Not white alone, not Hispanic or Latino

            03 = Hispanic or Latino

14-15


Current Residence State Name

16-45

Current Residence County Name

46-80

Population Current County – Estimate

82-89

Population Current County – MOE

91-98

Nonmovers Current County – Estimate

100-106

Nonmovers Current County – MOE

108-114

Movers within the United States for Current County or within Puerto Rico for Current Municipio – Estimate

116-122

Movers within the United States for Current County or within Puerto Rico for Current Municipio – MOE

124-130

Movers within the Same County for Current County – Estimates

132-138

Movers within the Same County for Current County – MOE

140-146

Movers from a Different County in the Same State for Current County – Estimate

148-154

Movers from a Different County in the Same State for Current County – MOE

156-162

Movers from a Different State for Current County – Estimate

164-170

Movers from a Different State for Current County – MOE

172-178

Movers from Abroad – Estimate

180-186

Movers from Abroad – MOE

188-194

Residence 1 Year Ago State Name/U.S. Island Areas/Foreign Region

196-225

Residence 1 Year Ago County Name

226-260

Population That Lived in County 1 Year Ago – Estimate

262-269

Population That Lived in County 1 Year Ago – MOE

271-278

Nonmovers County of Residence 1 Year Ago – Estimate

280-286

Nonmovers County of Residence 1 Year Ago– MOE

288-294

Movers within the United States. for County of Residence 1 Year Ago or within Puerto Rico for Municipio of Residence 1 Year Ago – Estimate

296-302

Movers within the United States for County of Residence 1 Year Ago or within Puerto Rico for Municipio of Residence 1 Year Ago – MOE

304-310

Movers within the Same County for County of Residence 1 Year Ago – Estimates

312-318

Movers within the Same County for County of Residence 1 Year Ago – MOE

320-326

Movers to a Different County in the Same State for County of Residence 1 Year Ago – Estimate

328-334

Movers to a Different County in the Same State for County of Residence 1 Year Ago – MOE

336-342

Movers to a Different State for County of Residence 1 Year Ago – Estimate

344-350

Movers to a Different State for County of Residence 1 Year Ago – MOE

352-358

Movers to Puerto Rico – Estimate

360-366

Movers to Puerto Rico – MOE

368-374

Movers within Flow – Estimate

376-382

Movers within Flow – MOE

384-390



County/MCD-to-County/MCD Flow Files


The County/MCD-to-County/MCD files are similar to the county-to-county files except that MCDs are used instead of counties for Connecticut, Maine, Massachusetts, Michigan, Minnesota, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, and Wisconsin.


There is one fixed field length national text file sorted by current residence geography. There is also an Excel file (.xlsx) containing a worksheet for each state of current residence, including Puerto Rico and the District of Columbia, and an another Excel file containing a worksheet for each state of residence 1 year ago.


In addition to the county or MCD of current residence, county or MCD of residence 1 year ago, and the number of movers between the two, the files also contain additional geographical mobility estimates for each county or MCD, along with the margin of error (MOE) at the 90 percent confidence level. (For further information about the geographies used for the files see Appendix A.)


The layout of the text file is as follows:

Field Description

Field Position

Current Residence FIPS State Code

1-3

Current Residence FIPS County Code

4-6

Current Residence FIPS MCD Code (CT, ME, MA, MN, MI, NH, NJ, NY, PA, RI, VT, WI only)

7-11

Residence 1 Year Ago FIPS State Code/U.S. Island Areas Code/Foreign Region Code

12-14

Residence 1 Year Ago FIPS County Code

15-17

Residence 1 Year Ago FIPS MCD Code (CT, ME, MA, MN, MI, NH, NJ, NY, PA, RI, VT, WI only)

18-22

Current Residence State Name

24-53

Current Residence County Name

54-88

Current Residence MCD Name (CT, ME, MA, MN, MI, NH, NJ, NY, PA, RI, VT, WI only)

89-133

Population 1 Year and Over Current County/MCD – Estimate

135-142

Population 1 Year and Over Current County/MCD – MOE

144-151

Nonmovers Current County/MCD – Estimate

153-159

Nonmovers Current County/MCD – MOE

161-167

Movers within the United States for Current County/MCD or within Puerto Rico for Current Municipio – Estimate

169-175

Movers within the United States for Current County/MCD or within Puerto Rico for Current Municipio – MOE

177-183

Movers within the Same County/MCD for Current County/MCD – Estimates

185-191

Movers within the Same County/MCD for Current County/MCD – MOE

193-199

Movers from a Different County/MCD in the Same State for Current County/MCD – Estimate

201-207

Movers from a Different County/MCD in the Same State for Current County/MCD – MOE

209-215

Movers from a Different State for Current County/MCD – Estimate

217-223

Movers from a Different State for Current County/MCD – MOE

225-231

Movers from Abroad – Estimate

233-239

Movers from Abroad – MOE

241-247

Residence 1 Year Ago State Name/U.S. Island Area/Foreign Region

249-278

Residence 1 Year Ago County Name

279-313

Residence 1 Year Ago MCD Name (CT, ME, MA, MN, MI, NH, NJ, NY, PA, RI, VT, WI only)

314-358

Population That Lived in County/MCD 1 Year Ago – Estimate

360-367

Population That Lived in County/MCD 1 Year Ago – MOE

369-376

Nonmovers County/MCD of Residence 1 Year Ago – Estimate

378-384

Nonmovers County/MCD of Residence 1 Year Ago– MOE

386-392

Movers within the United States for County/MCD of Residence 1 Year Ago or within Puerto Rico for Municipio of Residence 1 Year Ago – Estimate

394-400

Movers within the United States for County/MCD of Residence 1 Year Ago or within Puerto Rico for Municipio of Residence 1 Year Ago – MOE

402-408

Movers within the Same County/MCD for County/MCD of Residence 1 Year Ago – Estimates

410-416

Movers within the Same County/MCD for County/MCD of Residence 1 Year Ago – MOE

418-424

Movers to a Different County/MCD in the Same State for County/MCD of Residence 1 Year Ago – Estimate

426-432

Movers to a Different County/MCD in the Same State for County/MCD of Residence 1 Year Ago – MOE

434-440

Movers to a Different State for County/MCD of Residence 1 Year Ago – Estimate

442-448

Movers to a Different State for County/MCD of Residence 1 Year Ago – MOE

450-456

Movers to Puerto Rico – Estimate

458-464

Movers to Puerto Rico – MOE

466-472

Movers within Flow – Estimate

474-480

Movers within Flow – MOE

482-488




County/MCD-to-County/MCD Net and Gross Migration Files (No Characteristics)


There are two files, text and Excel, that contains flow, counterflow, net migration, and gross migration for all county/MCD pairs (Geography A and Geography B). The Excel file has a worksheet for each state. Both files are sorted by Geography A. The flow shows the inmigration from Geography B to Geography A. The counterflow shows the outmigration from Geography A to Geography B. The net migration is the flow minus the counterflow, and the gross migration is the flow plus the counterflow.


The layout for the text file is as follows:

Field Description

Field Position

State/U.S. Island Area/Foreign Region Code of Geography A (state code based on FIPS code)

1-3

FIPS County Code of Geography A

4-6

FIPS MCD Code of Geography A (CT, ME, MA, MN, MI, NH, NJ, NY, PA, RI, VT, WI only)

7-11

State/U.S. Island Area/Foreign Region Code of Geography B (state code based on FIPS code)

12-14

FIPS County Code of Geography B

15-17

FIPS MCD Code of Geography B (CT, ME, MA, MN, MI, NH, NJ, NY, PA, RI, VT, WI only)

 18-22

State/U.S. Island Area/Foreign Region Name of Geography A

24-53

County Name of Geography A

54-88

MCD Name of Geography A (CT, ME, MA, MN, MI, NH, NJ, NY, PA, RI, VT, WI only)

89-133

State/U.S. Island Area/Foreign Region Name of Geography B

134-163

County Name of Geography B

164-198

MCD Name of Geography B (CT, ME, MA, MN, MI, NH, NJ, NY, PA, RI, VT, WI only)

199-243

Flow from Geography B to Geography A – Estimate

245-252

Flow from Geography B to Geography A – MOE

254-261

Counterflow from Geography A to Geography B – Estimate

263-270

Counterflow from Geography A to Geography B – MOE

272-279

Net Migration from Geography B to Geography A – Estimate

281-288

Net Migration from Geography B to Geography A – MOE

290-297

Gross Migration between Geography A and Geography B – Estimate

299-306

Gross Migration between Geography A and Geography B – MOE

308-315



County/MCD-to-County/MCD Flow Files by Characteristics


There is a set of county/MCD-to-county/MCD files, text and Excel, for each of the three characteristics. The county/MCD-to-county/MCD characteristic flow files have the same fields as the county/MCD-to-county/MCD flow files with the additional field for characteristic code in positions 24-25. The field contains relationship to householder code, household type code, or housing tenure code depending upon the file.


The layout of the text file is as follows:


Field Description

Field Position

Current Residence FIPS State Code

1-3

Current Residence FIPS County Code

4-6

Current Residence FIPS MCD Code (CT, ME, MA, MN, MI, NH, NJ, NY, PA, RI, VT, WI only)

7-11

Residence 1 Year Ago FIPS State Code/U.S. Island Areas Code/Foreign Region Code

12-14

Residence 1 Year Ago FIPS County Code

15-17

Residence 1 Year Ago FIPS MCD Code (CT, ME, MA, MN, MI, NH, NJ, NY, PA, RI, VT, WI only)

18-22

Characteristic Code


Age Code:

            01 = 1 to 4 years

            02 = 5 to 17 years

            03 = 18 to 19 years

            04 = 20 to 24 years

            05 = 25 to 29 years

            06 = 30 to 34 years

            07 = 35 to 39 years

            08 = 40 to 44 years

            09 = 45 to 49 years

            10 = 50 to 54 years

            11 = 55 to 59 years

            12 = 60 to 64 years

            13 = 65 to 69 years

            14 = 70 to 74 years

            15 = 75 years and over


Sex Code:

            01 = Male

            02 = Female


Race Code:

            01 = White alone

            02 = Black or African American alone

            03 = Asian alone

            04 = Other race alone or Two or more races


Hispanic or Latino Origin:

            01 = White alone, not Hispanic or Latino

            02 = Not white alone, not Hispanic or Latino

            03 = Hispanic or Latino

24-25

Current Residence State Name

26-55

Current Residence County Name

56-90

Current Residence MCD Name (CT, ME, MA, MN, MI, NH, NJ, NY, PA, RI, VT, WI only)

91-135

Population Current County/MCD – Estimate

137-144

Population Current County/MCD – MOE

146-153

Nonmovers Current County/MCD – Estimate

155-161

Nonmovers Current County/MCD – MOE

163-169

Movers within the U.S. for Current County/MCD or within Puerto Rico for Current Municipio – Estimate

171-177

Movers within the U.S. for Current County/MCD or within Puerto Rico for Current Municipio – MOE

179-185

Movers within the Same County/MCD for Current County/MCD – Estimates

187-193

Movers within the Same County/MCD for Current County/MCD – MOE

195-201

Movers from a Different County/MCD in the Same State for Current County/MCD – Estimate

203-209

Movers from a Different County/MCD in the Same State for Current County/MCD – MOE

211-217

Movers from a Different State for Current County/MCD – Estimate

219-225

Movers from a Different State for Current County/MCD – MOE

227-233

Movers from Abroad – Estimate

235-241

Movers from Abroad – MOE

243-249

Residence 1 Year Ago State Name/U.S. Island Area/Foreign Region

251-280

Residence 1 Year Ago County Name

281-315

Residence 1 Year Ago MCD Name (CT, ME, MA, MN, MI, NH, NJ, NY, PA, RI, VT, WI only)

316-360

Population That Lived in County/MCD 1 Year Ago – Estimate

362-369

Population That Lived in County/MCD 1 Year Ago – MOE

371-378

Nonmovers County/MCD of Residence 1 Year Ago – Estimate

380-386

Nonmovers County/MCD of Residence 1 Year Ago– MOE

388-394

Movers within the U.S. for County/MCD of Residence 1 Year Ago or within Puerto Rico for Municipio of Residence 1 Year Ago – Estimate

396-402

Movers within the U.S. for County/MCD of Residence 1 Year Ago or within Puerto Rico for Municipio of Residence 1 Year Ago – MOE

404-410

Movers within the Same County/MCD for County/MCD of Residence 1 Year Ago – Estimates

412-418

Movers within the Same County/MCD for County/MCD of Residence 1 Year Ago – MOE

420-426

Movers to a Different County/MCD in the Same State for County/MCD of Residence 1 Year Ago – Estimate

428-434

Movers to a Different County/MCD in the Same State for County/MCD of Residence 1 Year Ago – MOE

436-442

Movers to a Different State for County/MCD of Residence 1 Year Ago – Estimate

444-450

Movers to a Different State for County/MCD of Residence 1 Year Ago – MOE

452-458

Movers to Puerto Rico – Estimate

460-466

Movers to Puerto Rico – MOE

468-474

Movers within Flow – Estimate

476-482

Movers within Flow – MOE

484-490




MSA-to-MSA Flow Files with No Characteristics


The MSA-to-MSA flow files are provided in two formats. There is one fixed field length national text file sorted by current residence geography. There is also an Excel file (.xlsx) containing flows between all the MSAs in the United States and Puerto Rico and the District of Columbia.


Besides the MSA of current residence, MSA of residence 1 year ago, and the number of movers between the two, the files also contain additional geographical mobility estimates for each MSA along with the margin of error (MOE) at the 90 percent confidence level. (For further information about the geographies used for the files see Appendix A.)


The layout of the text file is as follows:

Field Description

Field Position

Current Residence MSA Code (February 2013 delineations)

1-5

Residence 1 Year Ago MSA Code (February 2013 delineations)

6-10

Current Residence MSA Name

12-71

Population 1 Year and Over Current MSA – Estimate

73-80

Population 1 Year and Over Current MSA – MOE

82-89

Nonmovers Current MSA – Estimate

91-97

Nonmovers Current MSA – MOE

99-105

Movers within the Same MSA – Estimate

107-113

Movers within the Same MSA – MOE

115-121

Movers from a Different MSA for Current MSA – Estimate

123-129

Movers from a Different MSA for Current MSA – MOE

131-137

Movers from Elsewhere in the United States or Puerto Rico for Current MSA – Estimate

139-145

Movers from Elsewhere in the United States or Puerto Rico for Current MSA – MOE

147-153

Movers from Abroad (not including Puerto Rico) – Estimate

155-161

Movers from Abroad (not including Puerto Rico) – MOE

163-169

Residence 1 Year Ago MSA Name

171-230

Population That Lived in MSA 1 Year Ago – Estimate

232-239

Population That Lived in MSA 1 Year Ago – MOE

241-248

Nonmovers MSA of Residence 1 Year Ago – Estimate

250-256

Nonmovers MSA of Residence 1 Year Ago– MOE

258-264

Movers within the Same MSA – Estimate

266-272

Movers within the Same MSA – MOE

274-280

Movers to a Different MSA for MSA of Residence 1 Year Ago – Estimate

282-288

Movers to a Different MSA for MSA of Residence 1 Year Ago – MOE

290-296

Movers to Elsewhere in the United States or Puerto Rico for MSA of Residence 1 Year Ago – Estimate

298-304

Movers to Elsewhere in the United States or Puerto Rico for MSA of Residence 1 Year Ago – MOE

306-312

Movers within Flow – Estimate

314-320

Movers within Flow – MOE

322-328



MSA-to-MSA Net and Gross Migration Files (No Characteristics)


There are two files, text and Excel, that contains flow, counterflow, net migration, and gross migration for all msa pairs (Geography A and Geography B). The Excel file has a single worksheet for all flows. Both files are sorted by Geography A. The flow shows the inmigration from Geography B to Geography A. The counterflow shows the outmigration from Geography A to Geography B. The net migration is the flow minus the counterflow, and the gross migration is the flow plus the counterflow.


The layout for the text file is as follows:

Field Description

Field Position

MSA Code (February 2013 delineations) of Geography A

1-5

MSA Code (February 2013 delineations) of Geography A

6-10

MSA Name of Geography A

12-71

MSA Name of Geography A

72-131

Flow from Geography B to Geography A – Estimate

133-140

Flow from Geography B to Geography A – MOE

142-149

Counterflow from Geography A to Geography B – Estimate

151-158

Counterflow from Geography A to Geography B – MOE

160-167

Net Migration from Geography B to Geography A – Estimate

169-176

Net Migration from Geography B to Geography A – MOE

178-185

Gross Migration between Geography A and Geography B – Estimate

187-194

Gross Migration between Geography A and Geography B – MOE

196-203



MSA-to-MSA Flow Files by Characteristics


There is a set of MSA-to-MSA files, text and Excel, for each of the three characteristics. The MSA-to-MSA characteristic flow files have the same fields as the MSA-to-MSA flow files with the additional field for characteristic code in positions 12-13. The field contains relationship to householder code, household type code, or housing tenure code depending upon the file.


The layout of the text file is as follows:

Field Description

Field Position

Current Residence MSA Code (February 2013 delineations)

1-5

Residence 1 Year Ago MSA Code (February 2013 delineations)

6-10

Characteristic Code


Age Code:

            01 = 1 to 4 years

            02 = 5 to 17 years

            03 = 18 to 19 years

            04 = 20 to 24 years

            05 = 25 to 29 years

            06 = 30 to 34 years

            07 = 35 to 39 years

            08 = 40 to 44 years

            09 = 45 to 49 years

            10 = 50 to 54 years

            11 = 55 to 59 years

            12 = 60 to 64 years

            13 = 65 to 69 years

            14 = 70 to 74 years

            15 = 75 years and over


Sex Code:

            01 = Male

            02 = Female


Race Code:

            01 = White alone

            02 = Black or African American alone

            03 = Asian alone

            04 = Other race alone or Two or more races


Hispanic or Latino Origin:

            01 = White alone, not Hispanic or Latino

            02 = Not white alone, not Hispanic or Latino

            03 = Hispanic or Latino

12-13


Current Residence MSA Name

14-73

Population 1 Year and Over Current MSA – Estimate

75-82

Population 1 Year and Over Current MSA – MOE

84-91

Nonmovers Current MSA – Estimate

93-99

Nonmovers Current MSA – MOE

101-107

Movers within the Same MSA – Estimate

109-115

Movers within the Same MSA – MOE

117-123

Movers from a Different MSA for Current MSA – Estimate

125-131

Movers from a Different MSA for Current MSA – MOE

133-139

Movers from Elsewhere in the U.S. or Puerto Rico for Current MSA – Estimate

141-147

Movers from Elsewhere in the U.S. or Puerto Rico for Current MSA – MOE

149-155

Movers from Abroad (not including Puerto Rico) – Estimate

157-163

Movers from Abroad (not including Puerto Rico) – MOE

165-171

Residence 1 Year Ago MSA Name

173-232

Population That Lived in MSA 1 Year Ago – Estimate

234-241

Population That Lived in MSA 1 Year Ago – MOE

243-250

Nonmovers MSA of Residence 1 Year Ago – Estimate

252-258

Nonmovers MSA of Residence 1 Year Ago– MOE

260-266

Movers within the Same MSA – Estimate

268-274

Movers within the Same MSA – MOE

276-282

Movers to a Different MSA for MSA of Residence 1 Year Ago – Estimate

284-290

Movers to a Different MSA for MSA of Residence 1 Year Ago – MOE

292-298

Movers to Elsewhere in the U.S. or Puerto Rico for MSA of Residence 1 Year Ago – Estimate

300-306

Movers to Elsewhere in the U.S. or Puerto Rico for MSA of Residence 1 Year Ago – MOE

308-314

Movers within Flow – Estimate

316-322

Movers within Flow – MOE

324-330



Appendix A: Geography

County Equivalents

Counties are the primary legal division in most states, but a few states have equivalent divisions known by different names. In order to get a complete partition of the United States and Puerto Rico, the following divisions are treated as county equivalents in the files.

Borough (Alaska)

Census Area (Alaska)

City and Borough (Alaska)

County (All except Alaska, the District of Columbia, Louisiana, and Puerto Rico)

The District of Columbia

Independent City (Maryland, Missouri, Nevada, Virginia)[16]

Municipality (Alaska)                                                                 

Municipio (Puerto Rico)

Parish (Louisiana)


Minor Civil Divisions

The county/MCD-to-county/MCD files include minor civil division estimates for the 12 states in which they also serve as general-purpose local governments. The 12 states have various names for their minor civil divisions.


Connecticut (City, Town)

Maine (City, Gore, Indian Reservation, Plantation, Town, Unorganized Territory)

Massachusetts (City, Town)

Michigan (Charter Township, City, Township)

Minnesota (City, Township, Unorganized Territory)

New Hampshire (City, Grant, Location, Town, Township)

New Jersey (Borough, City, Purchase, Town, Township, Village)

New York (Borough, City, Indian Reservation, Town)

Pennsylvania (Borough, City, Town, Township)

Rhode Island (City, Town)

Vermont (City, Gore, Grant, Town)

Wisconsin (City, Town, Village)


Puerto Rico

Prior to the 2008 ACS, the stateside questionnaire only requested respondents to answer “Puerto Rico” if they lived in Puerto Rico 1 year ago. The Puerto Rico questionnaire asked for a municipio or a U.S. county for movers, along with other geographic information; therefore, municipio level migration flow data from Puerto Rico to the United States are not available prior to 2008 but are available for flow from the United States to each Puerto Rico municipio.

The question was revised in 2008 to ask for the same geographic information on the Puerto Rico and stateside questionnaire allowing estimates to be calculated for both flow directions. Because of this limitation, prior ACS county-to-county migration flow files aggregated flows from Puerto Rico to the United States to “Puerto Rico” rather than individual municipios. The 2008-2012 files are the first to include flows from Puerto Rico municipios to U.S. counties. Puerto Rico municipios are treated as equivalent to U.S. counties.


U.S. Island Areas and Foreign Countries

Outmigration from the United States and Puerto Rico to U.S. Island Areas or foreign countries is not available from the American Community Survey since only housing units and group quarters (e.g., college dormitories, military barracks, prisons) within the United States and Puerto Rico are sent questionnaires. The American Community Survey does collect data for U.S. Island Area or Foreign Country of residence 1 year ago. The files include inmigration from outside the United States and Puerto Rico aggregated to U.S. Island Areas and foreign region. A three letter code is used to identify these areas.


U.S. Island Areas (ISL):

American Samoa, Baker Island, Guam, Howland Island, Jarvis Island, Johnston Atoll, Kingman Reef, Northern Marianas Islands, Midway Islands, Navassa Island, Palmyra Atoll, U.S. Virgin Islands, Wake Island, U.S. Island Areas not specified.


Europe (EUR):

Albania, Andorra, Austria, Azores Islands, Belarus, Belgium, Bosnia and Herzegovina, Bulgaria, Croatia, Czechoslovakia, Czech Republic, Denmark, England, Estonia, Faroe Islands, Finland, France, Germany, Gibraltar, Greece, Guernsey, Hungary, Iceland, Ireland, Isle of Man, Italy, Jan Mayen, Jersey, Kosovo, Latvia, Liechtenstein, Lithuania, Luxembourg, Macedonia, Malta, Madeira Islands, Moldova, Monaco, Montenegro, Netherlands, Northern Ireland, Norway, Poland, Portugal, Romania, Russia, San Marino, Scotland, Serbia, Slovakia, Slovenia, Spain, Svalbard, Sweden, Switzerland, Ukraine, United Kingdom, USSR, Vatican City, Wales, Yugoslavia, Europe not specified.


Asia (ASI):

Afghanistan, Armenia, Azerbaijan, Bahrain, Bangladesh, Bhutan, Brunei, Cambodia, China, Cyprus, East Timor, Georgia, Hong Kong, India, Indonesia, Iran, Iraq, Israel, Japan, Jordan, Korea, Kazakhstan, Kyrgystan, Kuwait, Laos, Lebanon, Macau, Malaysia, Maldives, Mongolia, Myanmar (Burma), Nepal, North Korea, Oman, Pakistan, Paracel Islands, Philippines, Qatar, Saudi Arabia, Singapore, South Korea, Spratley Islands, Sri Lanka, Syria, Taiwan, Tajikistan, Thailand, Turkey, Turkmenistan, United Arab Emirates, Uzbekistan, Vietnam, Yemen, Asia not specified.


Northern America (NAM):

Bermuda, Canada, Greenland, St. Pierre & Miquelon, North American not specified


Central America (CAM):

Belize, Costa Rico, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, Panama, Central America not specified


Caribbean (CAR):

Anguilla, Antigua and Barbuda, Aruba, Bahamas, Barbados, Bonaire, British Virgin Islands, Cayman Islands, Cuba, Curaçao, Dominica, Dominican Republic, Grenada, Guadeloupe, Haiti, Jamaica, Martinique, Montserrat, Netherland Antilles, Saba, St. Barthelemy, St. Kitts-Nevis, St. Lucia, St. Vincent and the Grenadines, Sint Eustatius, Sint Maarten, Trinidad and Tobago, Turks and Caicos Islands, West Indies not specified


South America (SAM):

Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Falkland Islands, French Guiana, Guyana, Paraguay, Peru, Suriname, Uruguay, Venezuela, South American not specified


Africa (AFR):

Algeria, Angola, Benin, Botswana, British Indian Ocean Territory, Burkina Faso, Burundi, Cameroon, Cabo Verde, Central African Republic, Chad, Comoros, Congo, Democratic Republic of Congo, Djibouti, Egypt, Equatorial Guinea, Ethiopia, Eritrea, Europa Island, Gabon, Gambia, Ghana, Glorioso Islands, Guinea, Guinea-Bissau, Ivory Coast, Juan de Nova Island, Kenya, Lesotho, Liberia, Libya, Madagascar, Malawi, Mali, Mauritania, Mauritius, Mayotte, Morocco, Mozambique, Namibia, Niger, Nigeria, Reunion, Rwanda, Sao Tome and Principe, Senegal, Seychelles, Sierra Leone, Somalia, South Africa, South Sudan, St Helena, Sudan, Swaziland, Tanzania, Togo, Tromelin Island, Tunisia, Uganda, Western Sahara, Zambia, Zimbabwe, Africa not specified


Oceania and At Sea (OCE):

Australia, Christmas Island, Cook Islands, Coral Sea Islands, Heard and McDonald Islands, Fiji, French Polynesia, Kiribati, Marshall Islands, Micronesia, Nauru, New Caledonia, New Zealand, Niue, Norfolk Island, Palau, Papua New Guinea, Pitcairn Islands, Solomon Islands, Tokelau, Tonga, Tuvalu, Vanuatu, Wallis and Futuna Islands, Samoa, Oceania not specified, At sea



References:



Benetsky, Megan and Kin Koerber. 2005-2009 American Community Survey County-to-County Migration Files.

<http://www.census.gov/library/working-papers/2012/demo/benetsky-02.html>


Bortlein, Celia G. and Alan K. Peterson. Evaluation Report Covering Residence 1 Year Ago, 2007.

<http://www.census.gov/library/working-papers/2007/acs/2007_Boertlein_01.html>


U.S. Census Bureau. American Community Survey Design and Methodology (January 2014). Washington, D.C.: U.S Government Printing Office, 2014.

<http://census.gov/programs-surveys/acs/methodology/design-and-methodology.html>


U.S. Census Bureau. Puerto Rico Community Survey Multiyear Accuracy of the Data (5-year 2011-2015).

<https://www2.census.gov/programs-surveys/acs/tech_docs/accuracy/MultiyearACSAccuracyofData2015.pdf>


Zayatz, Laura. “Disclosure Avoidance Practices and Research at the U.S. Census Bureau: An Update.” Research Report Series 2005-06. Statistical Research Division, U.S. Census Bureau, Washington, D.C., August 31, 2005.

<http://census.gov/srd/papers/pdf/rrs2005-06.pdf>



[1] For additional background information about historical migration flows, see <http://www.census.gov/library/working-papers/2012/demo/benetsky-02.html>. For information about the various characteristics, see <http://www2.census.gov/programs-surveys/acs/tech_docs/subject_definitions/2015_ACSSubjectDefinitions.pdf>.

[2] The ACS program combines consecutive yearly datasets to increase the sample size and provide reliable estimates for smaller areas. Even though estimates are produced for 1-year datasets, they are limited to geographic areas of at least 65,000 population. Only the 5-year datasets provide estimates for all counties and county equivalents in the United States.

[3] The MSA delineations are from February 2013. See <https://www.census.gov/population/metro/> for more information.

[4] The Census Flows Mapper <http://flowsmapper.geo.census.gov/> is an interactive, online mapping application.

[5] The Census Developers site is located at <http://www.census.gov/developers/>.

[6] For more information on how Census data are protected see <http://census.gov/about/policies/privacy/data_protection.html>.

[7] Data swapping was the main procedure used for protecting Census 2000 tabulations and is also used for ACS tabulations. In each case, a small percentage of household records are swapped. Pairs of households in different geographic regions are swapped. The selection process for deciding which households should be swapped is highly targeted to affect the records with the most disclosure risk. Pairs of households that are swapped match on a minimal set of demographic variables. All data products are created from the swapped data files (American Community Survey Design and Methodology, 2015).

[8] County and MCD characteristic flows containing only one or two people from different households, only one or two people in group quarters, or one person in group quarters and the rest from a single household are suppressed. People are only counted if they are in universe (e.g., population 1 year and over in households for relationship to householder).

[9] Prior to the 2010-2014 release, some suppressed county and MCD flows were summed up to the state of residence 1 year ago. Those estimates are no longer included in the tables.

[10] The tables in AFF are crossed by age (B07001 and B07401), median age (B07002 and B07402), sex (B07003 and B07403), race and Hispanic origin (B07004A-I and B07404A-I), citizenship status (B07007 and B07407), marital status (B07008 and B07408), educational attainment (B07009 and B07409), individual income (B07010 and B07410), median individual income (B07011 and B07411), poverty status (B07012 and B07412), and housing tenure (B07013 and B07413). The stubs for the characteristic tables in AFF refer to movement between states and counties and not MCDs or MSAs.

[11] For more information concerning the calculation of margins of error, see chapter 12 of Design and Methodology: American Community Survey. <http://www2.census.gov/programs-surveys/acs/methodology/design_and_methodology/acs_design_methodology_report_2014.pdf>

[12] More on the model to compute ACS margins of error for zero-estimate counts can be found at <http://www2.census.gov/programs-surveys/acs/tech_docs/user_notes/KValueUserNote.pdf>.

[13] For more information on ACS group quarters small area estimation, see <http://www2.census.gov/programs-surveys/acs/tech_docs/user_notes/GQSAE_User_Note.pdf>.

[14] The Census Developers site is located at <http://www.census.gov/developers/>.

[15] For more information on geographic terms and concepts, see <http://census.gov/geo/www/reference.html>.

[16] In previous county-to-county flows products, some counties and independent cities were collapsed into single entities due to cognitive and geographic coding problems with migration data for places. (For the Census 2000 list of combined Virginia counties and independent cities see Appendix B in Migration DVD documentation at <http://census.gov/population/www/cen2000/migration/mig_dvd.html>).

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