The Census 2000 Supplementary Survey was designed to be used in combination with data from the American Community Survey comparison site tests to produceannual estimates. Economic, demographic, and housing characteristics from the Supplementary Surveys are reported for the United States as a whole, the 50 states, and the District of Columbia, as well as large counties and cities. The Census 2000 Supplementary Survey data provided an early look at the detailed characteristics of the U.S. population in 2000. However, as the official census sample data become available, they should be used instead of the Census 2000 Supplementary Survey to describe the population in 2000 and to look at changes from 1990 to 2000.

The Census 2000 Supplementary Survey (C2SS) tables are estimates of demographic and economic characteristics of people, households and housing units (occupied and vacant) for areas with a population of 250,000 or more.