The TIGER/Line shapefiles and related database files (.dbf) are an extract of selected geographic and cartographic information from the U.S. Census Bureau's Master Address File / Topologically Integrated Geographic Encoding and Referencing (MAF/TIGER) Database (MTDB). The MTDB represents a seamless national file with no overlaps or gaps between parts, however, each TIGER/Line shapefile is designed to stand alone as an independent data set, or they can be combined to cover the entire nation.

           A tribal census tract is a relatively permanent statistical subdivision of a federally recognized American Indian reservation and/or off-reservation
           trust land, delineated by the American Indian tribal government and/or the Census Bureau for the purpose of presenting demographic data. For the 2010
           Census, tribal census tracts are defined independently of the standard county-based census tract  delineation. For federally recognized American Indian
           Tribes with reservations and/or off-reservation trust lands with a population less than 2,400, a single tribal census tract is defined. Qualifying areas
           with a population greater than 2,400 could define additional tribal census tracts within their area. The tribal census tract codes for the 2010 Census
           are six characters long with a leading "T" alphabetic character followed by a five-digit numeric code, for example, T01000, which translates as tribal
           census tract 10. Tribal block groups nest within tribal census tracts. Since individual tabulation blocks are defined within the standard
           State-county-census tract geographic hierarchy, a tribal census tract can contain seemingly duplicate block numbers, thus tribal census tracts cannot be
           used to uniquely identify census tabulation blocks for the 2010 Census.

           The boundaries of tribal census tracts are those delineated through the Tribal Statistical Areas Program (TSAP) for the 2010 Census.