The 2010 tribal census tract concept and criteria are completely different from those used in 2000. Tribal census tracts (also known as tribal tracts) in 2000 were the standard state-county-census tract areas retabulated under an American Indian area hierarchy; that is, American Indian area-tribal census tract. Federally recognized tribes with a reservation or off-reservation trust land delineated tribal census tracts working with local census tract participants to produce a single census tract plan. Tribal census tracts were designed to be permanent statistical divisions of American Indian areas for the presentation of comparable data between censuses, particularly for those American Indian areas that crossed state or county boundaries where these boundaries were not meaningful for statistical purposes.
For 2010, tribal census tracts are defined independently of the standard county-based tract delineation. For federally recognized American Indian tribes with reservations or off-reservation trust land and 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.
In 2000, the tract number range of 9400 through 9499 was reserved for tribal census tracts and was required for those tribal census tracts that crossed state or county boundaries. Not all tribal census tracts in 2000, however, used this range. For 2010, tribal census tract codes will be six characters long with a leading "T" alphabetic character followed by five numeric codes having an implied decimal between the fourth and fifth character; for example, T01000, which translates as tribal census tract 10. Tribal block groups will nest within tribal census tract. Since individual blocks are defined within the standard statecounty-census tract hierarchy, a tribal census tract can contain seemingly duplicate block numbers, thus tribal census tracts cannot be used to uniquely identify census blocks.