TIGER GIS Data
TIGER (Topologically Integrated Geographic Encoding and Referencing) refers to the system and digital data base developed at the Census Bureau to support its mapping needs for the Decennial Census and other Bureau programs. Every 1-3 years the Census Bureau creates an extract from this data base and releases a TIGER update. These extracts are known as TIGER/Line files. The Libraries obtain the raw TIGER data as well as value-added versions of the data in, for example, ArcView shapefile format.
TIGER data include political and census boundaries (states, counties, tracts, block groups, blocks, zip code tabulation areas, urban boundaries, tribal subdivisions, Congressional districts, etc.) that can be used in conjunction with tabular data. TIGER also includes a wide range of feature data at a 1:100,000 scale (streets, hydrology, railroads, landmarks, etc.). For many locations, TIGER data are the only or easiest source for these features (especially for older dates). However, in many other cases, more recently updated and more positionally accurate data exists from other sources. Search the Libraries' GIS Data Collection or contact Data Services with questions.
As of the TIGER 2008 release, the native format for data is the shapefile. Previous to 2008, the format was called raw TIGER, which requires conversion to other readable formats. TIGER data are in geographic coordinates/decimal degrees and, starting with the 1995 release, uses the NAD 83 datum. [see the TIGER Overview]
More Census Related Webpages
> Census Guide - NCSU Libraries' starting point for finding Census data.
> Census Geographies Explained - Tracts, Block Groups, Blocks... what are they?
> Summary Files Explained - Short Form, Long Form, Decennial Census, American Community Survey... what do these mean?
> Population Census Guide of Printed Materials - In-depth year by year details starting with 1790 Census, and describes PRINT resources.
Need in-depth Census data assistance? Contact Data Services
TIGER 2000 data and some 1990 data are available as shapefiles for public access from: ESRI's Census 2000 TIGER/Line Data Download Page. Selected SF1 attributes may also be downloaded and joined to the shapefiles. See the Census 2000 page for additional information and sources of data.
TIGER 2000 data are available in raw format from the Census Bureau TIGER 2000 page. These data were used for the 2000 Census, and will most closely align with the 2000 Census tabular data.
What's the difference between the data on the ESRI Web site and the data on the Census Web site?
For the cartographic boundary files, the data from the Census site have been generalized from the original TIGER/Line data, whereas the files downloaded from ESRI still maintain the original detail.
Files on the Census site can also be downloaded by state and/or for the entire nation, depending on the layer. So if the generalization is acceptable, the Census site is the best source for large amounts of data. The Census Bureau (www.census.gov) also offers the files as shapefiles, Arc Info export files (.e00), and Arc Info ungenerate (ASCII) files.
For other geographic files (water, etc.) and for the attribute tables (PL-94 and SF1) that can be downloaded from ESRI, the Census site does not offer downloadable files that are ready to use with ESRI software. These geographic files are available only in TIGER format, so they have to be converted into a coverage or shapefile. The attribute files can only be downloaded from the Census site as huge text files that have to be reformatted, and that contain hundreds of attributes per file. ESRI extracted from these huge files only the attributes that were wanted and assigned meaningful names to the fields in the tables.
TIGER data for 1970 through 2000 may be extracted using the Libraries' GeoLytics software.
Also, numerous TIGER releases during the 1990's are available on CD-ROM in the Govt. Docs. CD cabinet in DH Hill Library. Search the catalog for the proper SuDoc call number and request assistance from a Reference Librarian for access.