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Accessing and Using the 2006 TIGER/Line Files Update 3/31/08. There have been important new developments affecting TIGER/Line files. The legacy TIGER/Line files are being replaced with TIGER/Line shapefiles. See the April 2008 DMINews for a brief description of how you can access and use TIGER/Line shapefiles. The 2006 Second Edition TIGER/Line (TGR2006Se) files became available in March 2007. There are now 1,871 counties and 78 Puerto Rico municipios that have realigned street feature coordinates resulting from the MAF/TIGER Accuracy Improvement Project. Of the 1,871 updated counties, 272 counties are new with the TGR2006FE files (others were released with the TIGER/Line 2004 and 2005 files). The TGR2006FE files reflect the latest available governmental unit boundaries (generally January 1, 2006). This updates the 2005 versions that reflect boundaries for governmental units as of January 1, 2005. Except for those counties with realigned street features, and updated governmental unit boundaries, the 2006 TIGER/Line files contain very few updates to street features or address ranges from the Census 2000 versions of the TIGER/Line files. The Census Bureau is realigning the street features in a portion of all counties/equivalent entities each year until all counties are completed in 2008. The Census Bureau has announced that the second edition 2006 TIGER/Line files will be the last of the TIGER/Line files to be released. Starting in the fall of 2007, the Census Bureau will replace TIGER/Line files with shapefiles and new geographic products. This Web page will provide updates as this transition occurs. How Different? Differences in geographic representation of the same features between the Census 2000 (TGR108) TIGER/Line and the 2006 TIGER/Line files (and corresponding shapefiles) vary dramatically. Here is an example for a section of San Diego, CA which typifies the overall county. Differences shown here are typical of the change in most of the counties having realigned street feature coordinates. The following graphic shows streets from the TGR108 (narrow lines) superimposed on the TGR2004 (wider lines). 
The following graphic shows census tracts from the TGR108 (narrow lines) superimposed on the TGR2004 (wider lines). 
Boundary Vintages. 2006 TIGER/Line files are based on the latest available governmental unit boundaries (January 1, 2006). Some legal boundaries and names are those reported to the Census Bureau to be legally in effect on January 1, 2000 (Census 2000 geographic areas) while others are updated and legally in effect as of the latest Boundary and Annexation Survey (BAS) (current geographic areas). The current boundaries represented in the 2006 TIGER/Line files are those reported to the Census Bureau by April 1, 2006 as being in effect as of January 1, 2006. The boundary information in the TIGER/Line files for both legal and statistical entities are for Census Bureau statistical data collection and tabulation purposes only; their depiction and designation for statistical purposes does not constitute a determination of jurisdictional authority or rights of ownership or entitlement. Key Geographic Changes. Since Census 2000 there have been changes in the universe of counties or statistically equivalent entities. In Colorado, Broomfield County was created from parts of Adams, Boulder, Jefferson, and Weld Counties. This change has resulted in the creation of a separate TIGER/Line file for Broomfield County, Colorado. In Virginia, the independent city of Clifton Forge changed its status to become Clifton Forge town and is now part of Alleghany County, Virginia; it appears in the Alleghany County, Virginia TIGER/Line file. Beginning with the 2002 TIGER/Line files, the Census Bureau no longer produces a TIGER/Line file for the Midway Islands. The 2006 TIGER/Line files include the Record Type M (new with 2005). Record Type M provides spatial metadata for each feature in a TIGER/Line file, identifying the source for the spatial coordinates. To avoid confusion with mixing of "current" state and county codes with decennial census tract and block numbers which are uniquely identified only by the decennial census state and county codes, the 2005 and later TLF editions provide Census 2000 codes on Record Type 1 even though the distribution unit for the post-Census 2000 TIGER/Line files is current county or statistically equivalent entity. Since some county or statistically equivalent entity boundaries have changed since Census 2000, the current boundaries may not match those used in Census 2000. Thus it is possible to find some territory that was in County A in the Census 2000 versions of the TIGER/Line files in the post-Census 2000 TIGER/Line file for County B. In counties or statistically equivalent entities that have gained territory, it is possible to have a complete chain that is a current county boundary and has the SIDE1 flag set, but has the same state and county codes on both sides of the complete chain. This occurs because a polygon that was, for example, in the Census 2000 TIGER/Line file for County A now is in the post-Census 2000 TIGER/Line file for County B. Since Record Type 1 displays the Census 2000 geography, the state and county code for County A (the county or statistically equivalent entity the lost territory) appears on this complete chain even though it currently is part of County B. The other side of this complete chain is in an adjacent TIGER/Line file and the U.S. Census Bureau appends the current state and county code of the adjacent county (County A) to this complete chain. The result is a complete chain that is a current county boundary yet has the same state and county codes on both sides of the complete chain. 109th Congressional Districts On Record Type A the Congressional District Code, Current field of the 2006 First Edition TIGER/Line files contains the 109th Congressional Districts. In a few cases the boundaries of the 109th Congressional districts do not follow Census 2000 block boundaries. Where the boundary of a congressional district for the 109th Congress splits a Census 2000 block, the Census Bureau's maps and TIGER/Line files depict the correct location of the boundary. For data tabulation purposes, that census block is allocated in its entirety to the 109th Congressional District specified to the Census Bureau by the state. This list provides all the 109th Congressional Districts that split census blocks and shows the congressional district where the block is allocated for data tabulation. See additional information on 109th Congressional Districts. Metropolitan and Micropolitan Statistical Areas appearing in the 2006 First Edition TIGER/Line files are those defined by the U.S. Office of Management and Budget (OMB) on June 6, 2003, and updated by various OMB notices since that time. goto top |
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