What are the TIGER/Line® Shapefiles?
What are the TIGER/Line Shapefiles?
1. How are the TIGER/Line Shapefiles created?
The TIGER/Line Shapefiles are extracts containing selected geographic and cartographic information from the Census Bureau's MAF/TIGER database. The MAF/TIGER database was developed at the Census Bureau to support a variety of geographic programs and operations including functions such as mapping, geocoding, and geographic reference files that are used in decennial and economic censuses and sample survey programs. Spatial data for geographic features such as roads, railroads, rivers, and lakes, as well as legal and statistical geographic areas are included in the product. Other information about these features, such as the name, the type of feature, address ranges, and the geographic relationship to other features, also are included. The TIGER/Line Shapefiles and associated relationship files are offered in a compressed format. One zipped file is available for each layer; it has a file extension of .zip. Each zipped shapefile consists of the following five files:
2. How are the TIGER/Line Shapefiles organized?
Geographic entities included in the Census Bureau's tabulations are generally hierarchical. The organizational structure of the TIGER/Line Shapefiles is based on this hierarchical framework (see diagram in [PDF] format or a [TEXT] description).
Shapefiles are released in up to four types of hierarchical coverages: American Indian Area-based, nation-based, state-based, and county-based. Some shapefiles are released in multiple coverages to increase flexibility of use. For more details about the most recent version of the files, see http://www.census.gov/geo/www/tiger/tgrshp2010/documentation.html.
3. What are the naming conventions for the TIGER/Line Shapefiles?
The name of each file is tl_<year>_<extent>_<layer>.<ext>
tl = TIGER/Line
<year> = the version of the files
<extent> = entity ID code of variable length; identifies the geographic extent of the file
<layer> = layer tag of variable length; identifies the type of geography or feature the file contains
<ext> = the file extension
4. If I can’t find the data aggregated the way I want on-line, can I order a custom product?
The shapefiles only are available in the format that you find on the website. We are unable to accommodate special requests for custom products. We welcome suggestions as to how we can make the TIGER/Line Shapefiles easier for our customers to use. Please email your comments to email@example.com.
5. The program I am working with does not read the shapefile format. Can I convert the TIGER/Line Shapefiles to another format?
The Census Bureau provides data in shapefile format only, and cannot assist with data conversion. If you require a different format, you may need to consult a private vendor that can perform conversion services.
6. How large are the TIGER/Line Shapefiles?
The size of each file varies greatly depending on the area and the type of geography it represents. The majority of the zipped files are less than 5 MB.
7. What specific types of geography or geographic features are contained in the TIGER/Line Shapefiles?
Please refer to the technical documentation page for the latest version of the files for more information about the available shapefiles.
8. Where can I find the record layout for the TIGER/Line Shapefiles?
The record layout for the latest version of the files is included in Appendix A of the 2010 TIGER/Line Shapefiles Technical Docmentation.
9. What datum are the shapefiles in?
Each shapefile contains a .prj file that contains the geographic information system (GIS) industry standard well-known text (WKT) format to describe the coordinate system/projection/datum information for each shapefile. This enables users to easily import the shapefiles into their local coordinate system. All of the 2008, 2009, and 2010 TIGER/Line Shapefiles are in GCS NAD83, and each .prj file contains the following:
In the 2007 TIGER/Line Shapefiles, the following areas had not gone through the NAD83 transformation process and were still within local astronomical datums: Hawaii County, Honolulu County (all areas except Oahu Island), Kalawao County, Kauai County, and Maui County in Hawaii; Eastern District, Manu'a District, Rose Island, Swains Island, and Western District in American Samoa; Guam; Northern Islands Municipality, Rota Municipality, Saipan Municipality, and Tinian Municipality in the Commonwealth of the Northern Mariana Islands. Please refer to the metadata associated with each file for further information.
10. What is the difference between the Census 2000 and current shapefiles in the 2007, 2008, and 2009 TIGER/Line Shapefiles?
The 2007, 2008, and 2009 TIGER/Line Shapefiles contain Census 2000 vintage geography and current geography. Census 2000 geography is defined as the geographic extent of legally defined geographic areas (boundaries of governmental units) or statistical areas in effect on January 1, 2000. At the time that these files were published, the Census Bureau had not systematically updated the inventory or boundaries of statistical areas since 2000; however, changes to legal areas may have affected statistical areas. Current geography is defined as the latest version of the geographic extent of legally defined geographic areas as reported, reflecting the boundaries of governmental units in effect as of January 1 of the year in the title of the shapefiles or legal and statistical area boundaries that have been adjusted and/or corrected since Census 2000.
11. What features does the All Lines shapefile contain?
The All Lines shapefile includes linear features such as roads, railroads, and hydrography. One All Lines shapefile exists for each county or equivalent entity. Additional attribute data associated with the linear features found in the All Lines shapefiles are available in relationship files that users must also download. The 2010 TIGER/Line Shapefiles also contain separate shapefiles containing just roads.
12. I can’t find a certain shapefile for my state/county. Is the data set incomplete?
The 2010 TIGER/Line Shapefiles are being released on a flow basis, not all at once. For the release schedule, please see http://www.census.gov/geo/www/tiger/tgrshp2010/release_schedule.html.
Note that the TIGER/Line Shapefiles do not include empty shapefiles. For example, if a state does not contain any consolidated cities, then no consolidated city shapefile is created for that state.
13. Are any of the boundary data in the TIGER/Line Shapefiles generalized?
No, the boundary data in the TIGER/Line Shapefiles are not generalized. However, generalized cartographic boundary files are available from the Census Bureau. These files are available for download from the Census Bureau's geography website at http://www.census.gov/geo/www/cob/bdy_files.html. More information on these files can be found in the answer to Frequently Asked Question #21, and at http://www.census.gov/geo/www/cob/index.html.
14. Do the TIGER/Line Shapefiles contain latitude and longitude coordinate information for the features they contain?
The coordinate information for the features contained in the shapefiles is not listed in the attribute tables, but is instead imbedded into the .shp portion of the shapefile itself.
15. Do the TIGER/Line Shapefiles contain point data indicating individual addresses?
No, the TIGER/Line Shapefiles do not contain point data for individual addresses. For reasons of confidentiality, under Title 13 of the U.S. Code, the U.S. Census Bureau is not permitted to release individual addresses or geographic coordinates for individual addresses. The only address-related information that we can release are the potential address ranges along street segments found in our TIGER/Line Shapefiles.
16. Are there data in the TIGER/Line Shapefiles that will enable me to geocode addresses?
The TIGER/Line Shapefiles include left- and right-side most-inclusive address ranges in the All Lines shapefile. The Census Bureau identifies the most-inclusive address ranges as the address ranges that contain the largest number of possible house numbers (potential addresses). The number of possible house numbers reflects the parity of the address range and the difference between from- and to- house numbers. The most-inclusive address ranges are not summary or generalized address ranges where data from several ranges have been collapsed bridging gaps between address ranges.
To get the best match results, the Census Bureau advises data users to use all of the available address ranges to geo-reference/geocode addresses, including those in the Addres Ranges relationship file. A single pair of left- and right-side address ranges may not always provide complete address range coverage. The address ranges in the TIGER/Line Shapefiles may be separate because of ZIP Code differences or to establish gaps created by out-of-sequence addresses located elsewhere. Some address ranges may include embedded alphanumeric characters or hyphens that make them distinct from the other address ranges.
The Census Bureau does not provide or support address geocoding software.
17. The Address Range relationship file often lists several address ranges for each edge. Which address ranges should I use to geocode addresses?
In many cases, the most-inclusive address ranges (found in the All Lines shapefiles) may cover the available address ranges for an edge. However, the Census Bureau advises data users to use all of the available address ranges to geo-reference/geocode addresses for the best possible results. A single pair of left- and right-side address range may not always provide complete address range coverage. The address ranges in the TIGER/Line Shapefiles may be separate because of ZIP Code differences or to establish gaps created by out-of-sequence addresses located elsewhere. Some address ranges may include embedded alphanumeric characters or hyphens that make them distinct from the other address ranges. Only using one of the available address ranges will significantly lower the overall address match success rate.
18. How do I link together all the addresses I need for geocoding?
Users can link the All Lines shapefile with the Address Ranges relationship file on the similar TLID field. Please be aware that multiple address ranges can apply to the same edge (one edge can have multiple address ranges associated with it).
19. Do the TIGER/Line Shapefiles contain demographic data?
No, the shapefiles do not contain demographic data. Users must download demographic data separately and incorporate it into the shapefiles. Census Bureau demographic data are available through American FactFinder. Please see our Working With TIGER/Line Shapefiles series of brochures for information on how to do this.
20. Can I merge the TIGER/Line Shapefiles and the Census Bureau’s demographic data?
The TIGER/Line Shapefiles contain geographic entity codes such as state, county, tract, block, etc., as appropriate. Demographic data files also contain these codes. Users can utilize these codes to merge the TIGER/Line Shapefiles and the Census Bureau's demographic data. Please see our Working With TIGER/Line Shapefiles series of brochures for information on how to do this.
21. How are the TIGER/Line Shapefiles different from the Cartographic Boundary Files?
Unlike the Cartographic Boundary Files, the shapefiles are NOT generalized. The Cartographic Boundary Files are generalized extracts from our geographic database and are designed primarily for small scale thematic mapping. If you overlay the generalized Cartographic Boundary Files over the TIGER/Line Shapefiles, the boundaries will not precisely line up because of the generalization. The Cartographic Boundary Files are also clipped back to the shoreline of the U.S, while the TIGER/Line Shapefiles show the full extent of geography out to the 3-mile limit of coastal water. The shapefiles also are available down to the block level, whereas the Cartographic Boundary Files are only available down to the block group.
22. Where can I find information about MAF/TIGER Feature Class Codes (MTFCCs)?
The metadata files associated with each shapefile or relationship file contain some information about MTFCCs. Appendix F of the 2010 TIGER/Line Shapefile Technical Documentation also contains information about these codes.
23. Where do I get the TIGER/Line Shapefiles and detailed information about the spatial data set?
The 2010 TIGER/Line Shapefiles are the latest release of the shapefiles, and the files and associated technical documentation are available for download free of charge on the 2010 TIGER/Line Shapefiles main page . To use the data, you must have a Geographic Information System (GIS) software package that can display shapefiles.
24. Will the Census Bureau release updated TIGER/Line Shapefiles to the public periodically? If so, what is the schedule for their release?
As we have done in recent years, we plan to release a new edition of the shapefiles approximately once per year. The 2010 TIGER/Line Shapefiles will be released on a flow basis beginning in December of 2010. For more information, please see the release schedule.
25. Are previous versions of the TIGER/Line data still available?
The 2007, 2008, and 2009 TIGER/Line Shapefiles are still available online. The following versions of the TIGER/Line files (in ASCII text format) are also still available online: Census 2000, Redistricting Census 2000, UA Census 2000, and 2006 Second Edition. For other versions of the TIGER/Line files, please contact our Customer Services Center at 1 (800) 923-8282.
26. Who do I contact if I have questions about the TIGER/Line Shapefiles?
If you have questions about the shapefiles, please call the Geographic Products Branch at the US Census Bureau at (301) 763-1128 or send an email to firstname.lastname@example.org.
27. Are the TIGER/Line Shapefiles copyrighted? Can I reproduce them?
By law, Title 17 U.S.C., Section 105, copyright protection is not available for any work of the United States Government. Thus, the U.S. Government is precluded from copyrighting its publications. Consequently, you are free to reproduce Census Bureau materials as you see fit. However, TIGER® and TIGER/Line® are registered trademarks of the U.S. Census Bureau; ZCTA™ is also a trademark of the U.S. Census Bureau. As such, these names cannot be used as or within the proprietary product names of any commercial product including or otherwise relevant to U.S. Census Bureau data, and may only be used to refer to the nature of such product. The U.S. Census Bureau requests that any repackaging of the TIGER/Line Shapefile data (and documentation) and other files accompanying it for distribution include a conspicuously placed statement to this effect on the product's cover, the first page of the website, or elsewhere of comparable visibility. Further, U.S. Census Bureau trademarks, when used in reference to the nature of the product, should be accompanied by the ® (registered) symbol or ™ symbol.
28. Are the TIGER/Line Shapefiles available on CD or DVD?
At this time, with the exception of DVDs produced and delivered as part of the Redistricting Data Program, we do not plan to create any CDs or DVDs containing the TIGER/Line Shapefiles. However, the latest version of the files may be downloaded via FTP at ftp://ftp2.census.gov/geo/tiger/TIGER2010/.
29. Where do I find metadata associated with the TIGER/Line Shapefiles?
The metadata are packaged with the shapefiles and relationship files. The metadata files associated with the shapefiles have the extension .shp.xml, and those associated with the relationship files have the extension .dbf.xml. The metadata are FGDC compliant and are also available on the Geospatial One Stop.
30. How do I view the metadata for the TIGER/Line Shapefiles without the XML tags?
You can use the Metadata Validation Service from the USGS to view the metadata without the XML tags. Use ‘Browse’ to select a file to validate, and then click ‘Validate’. On the results page, pick ‘Text’ from the output list.