What are the TIGER/Line® Shapefiles?
Data Format
Content
Dissemination
Metadata
What are the TIGER/Line Shapefiles?
1. How were the TIGER/Line Shapefiles created?
The 2007 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?
The shapefiles are organized based on the Census Bureau’s hierarchical relationship of geographic entities (see diagram in [PDF] format or a [TEXT] description). Entities that are defined independently from states and counties, such as ZIP Code Tabulation Areas, are available in nation-based shapefiles that encompass the entire country. Entities such as school districts and congressional districts that are defined within states but can cross county boundaries are represented in state-based shapefiles (i.e. one shapefile for each state). Entities that are defined within counties and do not cross county or state lines (such as census tracts, block groups, and blocks) are represented in county-based shapefiles. This differs from the TIGER/Line files, which were available exclusively in county-based files. For more details about the organization of the files, visit http://www.census.gov/geo/www/tiger/tgrshp2007/tgrshp2007org.html.
3. What are the naming conventions for the TIGER/Line Shapefiles?
The following diagram explains each portion of the file name.
[D]
4. How are the TIGER/Line Shapefiles different from the TIGER/Line files?
With the modernization of the Master Address File (MAF) and Topologically Integrated Geographic Encoding and Referencing (TIGER) databases from our home-grown database to an Oracle relational database, the Census Bureau has decided to replace the TIGER/Line files, which were ASCII text format, with the new TIGER/Line Shapefiles. The shapefiles contain information similar to what is found in the TIGER/Line files. For detailed information about the contents of the shapefiles, refer to the record layout, available in [PDF] and [TEXT] formats.
Data Format
Since the Census Bureau first developed the TIGER/Line files, shapefiles have evolved into the de facto industry standard format for geospatial data. The vast majority of TIGER/Line users convert the data into shapefile format for use with their applications. Presenting the data in shapefile format will make it more readily usable.
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 tiger@census.gov.
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. Please see the TIGER Vendors List for a list of companies that provide products and services related to TIGER.
8. How large are the TIGER/Line Shapefiles?
The TIGER/Line Shapefiles are larger than the TIGER/Line files. 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.
Content
Please refer to the record layout, available in [PDF] and [TEXT] formats, for a listing of all of the available shapefiles.
10. Where can I find the record layout for the TIGER/Line Shapefiles?
Links to the record layout in [PDF] and [TEXT] formats are posted on the 2007 TIGER/Line Shapefiles main page .
11. 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. Most Census Bureau generated shapefiles are in GCS NAD83, and each .prj file contains the following:
GEOGCS["GCS_North_American_1983",DATUM["D_North_American_1983",SPHEROID["GRS_1980",6378137,298.257222101]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519943295]]
The following areas have not gone through the NAD83 transformation process and are 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.
12. What is the difference between the Census 2000 and current shapefiles?
The 2007 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. The Census Bureau has not systematically updated the inventory or boundaries of statistical areas since 2000, however, changes to legal areas may affect 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, 2007, or legal and statistical area boundaries that have been adjusted and/or corrected since Census 2000.
13. 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.
14. Why are the 2007 TIGER/Line Shapefiles called 2007 when they were released in 2008?
The year noted in the version of the TIGER/Line Shapefile represents the vintage of the boundaries in the file. Thus, the current 2007 TIGER/Line Shapefiles contain the boundaries for governmental units as of January 1, 2007 as reported in the 2007 Boundary and Annexation Survey.
15. When will the street features in my county be realigned?
The U.S. Census Bureau began a multi-year project in 2002 to realign and update street features in our geographic database, called the MAF/TIGER Accuracy Improvement Project (MTAIP). We are realigning and updating the street features by county (or statistically equivalent entities) and we expect to complete this activity for all of the nation's counties in 2008. State, tribal, county, and local governments submitted over 2,000 files, which we are using as our sources to perform the realignment and feature update work. In other counties, we are performing the work using recently obtained imagery and/or driving the counties with GPS enhanced mapping equipment.
The realignment and update project is not complete. Therefore, some counties in the 2007 TIGER/Line Shapefiles do not contain realigned and updated street features in the All Lines shapefile. Even though the current version of these shapefiles do not reflect the realignment and feature update work, you will see the enhancements in subsequent versions. A list of the counties not realigned and updated with new features in the 2007 TIGER/Line Shapefiles is available from http://www.census.gov/geo/www/tiger/tgrshp2007/tgrshp07nomtaip.txt.
16. I can’t find a certain shapefile for my state/county. Is the data set incomplete?
No, the data set is not incomplete. The TIGER/Line Shapefiles do not include empty shapefiles. For example, if a state does not contain any consolidated cities, then no Current Consolidated City shapefile or Census 2000 Consolidated City shapefile is created for that state.
17. Are any of the boundary data in the TIGER/Line Shapefiles generalized?
No, the boundary data in the TIGER/Line Shapefiles are not generalized.
The coordinate information for the features contained in the shapefiles is not listed in the record layout, but is instead imbedded into the .shp portion of the shapefile itself.
19. 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.
The 2007 TIGER/Line Shapefiles do not provide left- and right-side most-inclusive address ranges. However, these address ranges will be populated in future releases. 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. 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.
The Census Bureau does not provide or support address geocoding software.
In many cases, the most-inclusive address ranges 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.
The most inclusive address ranges in the TIGER/Line All Lines shapefile are comparable to the address ranges on RT-1 in the TIGER/Line files. In addition, the TIGER/Line Address Ranges relationship file contains the full complement of publicly releasable address ranges, which is comparable to RT-6 in the TIGER/Line files. For both products, the Census Bureau advises data users to use the full set of address ranges from the Address Ranges Relationship File address ranges to obtain the best address matching results.
The MAF/TIGER Database that provides the data for the TIGER/Line Shapefiles does not permanently maintain a set of left- and right-side most-inclusive address ranges (note that these were not defined for the 2007 product release). The Census Bureau identifies the most-inclusive address ranges prior to TIGER/Line Shapefile generation. In many cases, the most-inclusive address ranges in All Lines shapefile will be the same as the address ranges on RT-1 in the TIGER/Line files. However, differences will occur as a result of differences in the address ranges and the method of determining the most-inclusive address ranges.
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.
23. 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).
24. Do the 2007 TIGER/Line Shapefiles contain address ranges that are new since Census 2000?
The 2007 TIGER/Line Shapefiles do contain some new address ranges that have been added since Census 2000. However, the dataset has not been completely updated. Therefore, new address ranges may be included in some areas but not others.
Generally, TLIDs have remained the same between the 2006 Second Edition TIGER/Line files and the 2007 TIGER/Line Shapefiles. In some cases, lines that have been split or redrawn have been assigned new TLIDs. Throughout the realignment process that was part of the MAF/TIGER Accuracy Improvement Project, TLIDs remained the same with one exception. That is, if an existing edge could not be spatially corrected by moving it, then it would be deleted and redrawn. The newly created line would be assigned a new TLID.
26. Do the TIGER/Line Shapefiles contain demographic data?
No, the shapefiles do not contain demographic data.
27. 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.
28. 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.
29. 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. More information is available from the 2007 TIGER/Line Shapefiles main page, including a crosswalk relating MTFCCs to their predecessors, Census Feature Class Codes (CFCCs).
30. Why did the Census Bureau switch from CFCCs to MTFCCs?
The switch from CFCCs to MTFCCs was intended to streamline our road classification system. It was often difficult to accurately maintain road feature classification using CFCCs. Definitions were vague and it was often hard to determine which classification best suited a particular feature. Features were not always classified consistently. To eliminate these problems, the classification system has been restructured and simplified. For example, CFCCs A2 and A3 were combined into MTFCC S1200.
Dissemination
31. Where do I get the TIGER/Line Shapefiles and detailed information about the spatial data set?
The 2007 TIGER/Line Shapefiles are the first release of the shapefiles, and the files and associated technical documentation are available for download free of charge on the 2007 TIGER/Line Shapefiles main page . To use the data, you must have a Geographic Information System (GIS) software package that can display shapefiles.
The first release of the TIGER/Line Shapefiles (2007 version) was in early 2008. We plan to release a new edition of the shapefiles approximately once per year.
The release of TIGER/Line files in ASCII format has been discontinued. The last version, the 2006 Second Edition TIGER/Line files, was posted to our web site in March 2007.
34. Are previous versions of the TIGER/Line files still available?
The TIGER/Line Shapefiles supersede the previous TIGER/Line format. However, the Census 2000, Redistricting Census 2000, and UA Census 2000 versions of the TIGER/Line files will remain available on our website. The last release of the TIGER/Line files, the 2006 Second Edition, will remain available online as well. For other versions of the TIGER/Line files, please contact our Customer Services Center at 1 (800) 923-8282.
Yes, the Census Bureau plans to continue to provide Cartographic Boundary Files. You can download these files and find more information about them from the Cartographic Boundary Files main page.
36. 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 tiger@census.gov.
37. 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 Government is precluded from copyrighting its publications. Consequently, you are free to reproduce census 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.
38. Are the 2007 TIGER/Line Shapefiles available on CD or DVD?
At this time, we do not plan to create any CDs or DVDs containing the 2007 TIGER/Line Shapefiles. However, the files may be downloaded via FTP at ftp://ftp2.census.gov/geo/tiger/TIGER2007FE/.
Metadata
39. Where do I find metadata associated with the TIGER/Line Shapefiles?
The metadata is 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 is FGDC compliant and is also available on the Geospatial One Stop.
40. 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.
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To view the file, you will need the
Adobe® Acrobat® Reader
available free from Adobe.
