Data were originally developed and supplied by US Bureau of Census. The TIGER/Line Files are shapefiles and related database files (.dbf) that 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 File is designed to stand alone as an independent data set, or they can be combined to cover the entire nation.
County subdivisions are the primary divisions of counties and their equivalent entities for the reporting of Census Bureau data, and they include legally minor civil divisions (MCDs) and statistical census county divisions (CCDs), and unorganized territories. For the 2010 Census, the legal MCDs are the primary governmental and/or administrative divisions of counties in 29 States and Puerto Rico; Tennessee changed from having CCDs for Census 2000 to having MCDs for the 2010 Census. In MCD States where no MCD exists or is not defined, the Census Bureau creates statistical unorganized territories to complete coverage. The entire area of the United States, Puerto Rico, and the Island Areas is covered by county subdivisions. The boundaries of all 2010 Census legal MCDs are as of January 1, 2010 as reported through the Census Bureau's Boundary and Annexation Survey (BAS). For the 2010 Census, CCDs or their equivalents are delineated in 21 States. The boundaries of all 2010 Census statistical CCDs were delineated as part of the Census Bureau's Participant Statistical Areas Program (PSAP).