Skip Header

Block Assignment Files Record Layout

2020 Census Block Assignment Files

The Census Bureau's Redistricting Data Products provide the states and other data users with the small area census data necessary for legislative redistricting. Among the geographic products disseminated for the 2020 Census are the Block Assignment Files (BAFs), corresponding Name Look-up Tables (NLTs), and Block Relationship Files (BRFs).

BAFs have been created for each of the 50 states, the District of Columbia, and the Commonwealth of Puerto Rico.  Each file contains 2020 Census tabulation block codes and geographic area codes for a specific geographic entity type.  Each BAF contains every block within the given state, even if the block is not within one of the geographic areas represented in the file.  For those blocks where no geographic area is present, the block is listed, followed by one or more pipe delimiters (depending on the file layout for the specific geographic area type). BAFs are not created for a geography type when that geography type does not exist in the state.

File Format

BAFs are pipe delimited text (.txt) files.  The first line of each BAF is the field header.  The 10 types of BAFs and the fields they contain are described below:

Geographic Area <entity> Field Layout
Congressional districts CD BLOCKID|DISTRICT
State legislative districts - upper SLDU BLOCKID|DISTRICT
State legislative districts - lower SLDL BLOCKID|DISTRICT
Voting districts VTD BLOCKID|COUNTYFP|DISTRICT
Elementary school districts SDELM BLOCKID|DISTRICT
Secondary school districts SDSEC BLOCKID|DISTRICT
Unified school districts SDUNI BLOCKID|DISTRICT
Incorporated places / census designated places INCPLACE_CDP BLOCKID|PLACEFP
American Indian / Alaska Native / Native Hawaiian areas AIANNH BLOCKID|AIANNHCE|COMPTYPE
Minor Civil Divisions MCD BLOCKID|COUNTYFP|COUSUBFP

Field Definitions

BAF field definitions are as follows:

  • BLOCKID:  15-character code that is the concatenation of fields consisting of the 2-character state FIPS code, the 3-character county FIPS code, the 6-character census tract code, and the 4-character tabulation block code.
  • DISTRICT:  variable length code representing the district (i.e., geographic area)
    • CD - 2-character code
    • SLDU - 3-character code
    • SLDL - 3-character code
    • VTD - 6-character code
    • SDELM - 5-character code
    • SDSEC - 5-character code
    • SDUNI - 5-character code
  • PLACEFP:  5-character place FIPS code
  • AIANNHCE:  4-character American Indian / Alaska Native / Native Hawaiian (AIANNH) area census code
  • COMPTYPE:  1-character code indicating that if a block is within an AIANNH area, whether that area is represented as off-reservation trust land (T) or all other types (R).
  • COUNTYFP:  3-character county FIPS code
  • COUNTYSUBFP:  5-character county subdivision FIPS code

2020 Redistricting Data Prototype (P.L. 94-171) Block Assignment Files (BAFs): 2018 End-to-End Test

The 2020 Redistricting Data Prototype (P.L. 94-171) Block Assignment Files (BAFs): 2018 End-to-End Test and corresponding Name Lookup Tables are created for Providence County, Rhode Island specifically for use by states to help them prepare for redistricting following the 2020 Census. The Census Redistricting Data Program releases prototype Census data, TIGER/Line shapefiles, and maps in advance of the actual releases from the 2020 Census for the purpose of providing states and other stakeholders the opportunity to build their redistricting systems. By doing so, states can load the final 2020 Census geography and data upon receipt in early 2021 and immediately begin the redistricting process. BAFs will be created for each of the 50 states, the District of Columbia, and the Commonwealth of Puerto Rico. Each file will contain 2020 Census tabulation block codes and geographic area codes for a specific geographic entity type. Each BAF will contain every block within the given state, even if the block is not within one of the geographic areas represented in the file. For those blocks where no geographic area is present, the block is listed, followed by one or more line breaks (depending on the file layout for the specific geographic area type). The 2020 Redistricting Data Prototype (P.L. 94-171) BAFs: 2018 End-to-End Test contain data for Providence, RI only.

File Format

BAFs are pipe delimited text (.txt) files.  The first line of each BAF is the field header.  The 10 types of BAFs and the fields they contain are described below:

Geographic Area <entity> Field Layout
Congressional districts CD BLOCKID|DISTRICT
State legislative districts - upper SLDU BLOCKID|DISTRICT
State legislative districts - lower SLDL BLOCKID|DISTRICT
Voting districts VTD BLOCKID|COUNTYFP|DISTRICT
Elementary school districts SDELM BLOCKID|DISTRICT
Secondary school districts SDSEC BLOCKID|DISTRICT
Unified school districts SDUNI BLOCKID|DISTRICT
Incorporated places / census designated places INCPLACE_CDP BLOCKID|PLACEFP
American Indian / Alaska Native / Native Hawaiian areas AIANNH BLOCKID|AIANNHCE|COMPTYPE
Minor Civil Divisions MCD BLOCKID|COUNTYFP|COUSUBFP

Field Definitions

Field definitions are as follows:

  • BLOCKID:  15-character code that is the concatenation of fields consisting of the 2-character state FIPS code, the 3-character county FIPS code, the 6-character census tract code, and the 4-character tabulation block code.
  • DISTRICT:  variable length code representing the district (i.e., geographic area)
    • CD - 2-character code
    • SLDU - 3-character code
    • SLDL - 3-character code
    • VTD - variable length code of up to 6 characters
    • SDELM - 5-character code
    • SDSEC - 5-character code
    • SDUNI - 5-character code
  • PLACEFP:  5-character place FIPS code
  • AIANNHCE:  4-character American Indian / Alaska Native / Native Hawaiian (AIANNH) area census code
  • COMPTYPE:  1-character code indicating that if a block is within an AIANNH area, whether that area is represented as off-reservation trust land (T) or all other types (R).
  • COUNTYFP:  3-character county FIPS code
  • COUNTYSUBFP:  5-character county subdivision FIPS code

2010 Census Block Assignment Files

The Census Bureau's Redistricting Data Products provide the states and other data users with the small area census data necessary for legislative redistricting.  Among the geographic products disseminated for the 2010 Census are the Block Assignment Files (BAFs) and corresponding Name Look-up Tables (NLTs).

BAFs have been created for each of the 50 states, the District of Columbia, and the Commonwealth of Puerto Rico.  Each file contains 2010 Census tabulation block codes and geographic area codes for a specific geographic entity type.  Each BAF contains every block within the given state, even if the block is not within one of the geographic areas represented in the file.  For those blocks where no geographic area is present, the block is listed, followed by one or more commas (depending on the file layout for the specific geographic area type).

File Format

BAFs are comma delimited text (.txt) files.  The first line of each BAF is the field header.  The nine types of BAFs and the fields they contain are described below:

Geographic Area <entity> Field Layout
Congressional districts CD BLOCKID,DISTRICT
State legislative districts - upper SLDU BLOCKID,DISTRICT
State legislative districts - lower SLDL BLOCKID,DISTRICT
Voting districts VTD BLOCKID,COUNTYFP,DISTRICT
Elementary school districts SDELM BLOCKID,DISTRICT
Secondary school districts SDSEC BLOCKID,DISTRICT
Unified school districts SDUNI BLOCKID,DISTRICT
Incorporated places / census designated places INCPLACE_CDP BLOCKID,PLACEFP
American Indian / Alaska Native / Native Hawaiian areas AIANNH BLOCKID,AIANNHCE,COMPTYPE

Field Definitions

Field definitions are as follows:

  • BLOCKID:  15-character code that is the concatenation of fields consisting of the 2-character state FIPS code, the 3-character county FIPS code, the 6-character census tract code, and the 4-character tabulation block code.
  • DISTRICT:  variable length code representing the district (i.e., geographic area)
    • CD - 2-character code
    • SLDU - 3-character code
    • SLDL - 3-character code
    • VTD - variable length code of up to 6 characters
    • SDELM - 5-character code
    • SDSEC - 5-character code
    • SDUNI - 5-character code
  • PLACEFP:  5-character place FIPS code
  • AIANNHCE:  4-character American Indian / Alaska Native / Native Hawaiian (AIANNH) area census code
  • COMPTYPE:  1-character code indicating that if a block is within an AIANNH area, whether that area is represented as off-reservation trust land (T) or all other types (R).
  • COUNTYFP:  3-character county FIPS code

Related Information


Top

Back to Header