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.
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.