Topologically Integrated Geographic Encoding and Referencing

Topologically Integrated Geographic Encoding and Referencing, or TIGER, or TIGER/Line is a format used by the United States Census Bureau to describe physical and cultural features such as roads, highways, city limits, rivers, and lakes, as well as areas such as census tracts. TIGER was developed to support and improve the Bureau's process of taking the Decennial Census.— Developed in collaboration with the United States Geological Survey during the 1980's, TIGER was the first nationwide digital map of roads, boundaries and water and was initially created for the 1990 Census to modernize the once-a-decade head count. However, its impact has extended well beyond its initial purpose by offering common map data in electronic form that powers today’s geographic information system industry. TIGER still serves as the basemap for many commercial and open-source map projects in very rural areas of the United States. However, commercial mapping companies now offer newer and more detailed mapping data in urban and high growth areas.

The TIGER files do not contain the census demographic data, but merely the geospatial/map data. GIS can be used to merge census demographics or other data sources with the TIGER files to create maps and conduct analysis. TIGER data is available without cost because U.S. Government publications are required to be released into the public domain. Provided by Wikipedia