Historic Snapshot of the Nation
The official U.S. Census is described in Article I, Section 2 of the Constitution of the United States. It calls for an actual enumeration of the people every ten years, to be used for apportionment of seats in the House of Representatives among the states. The first official Census was conducted in 1790 under Thomas Jefferson, who was the Secretary of State. That census, taken by U.S. marshals on horseback, counted 3.9 million inhabitants. Since that time, the decennial Census has been conducted every ten years, generally on April 1 in years ending in a zero.
Besides providing the basis for congressional redistricting, Census data are used in many other ways. Since 1975, the Census Bureau has had responsibility to produce small-area population data needed to redraw state legislative and congressional districts. Other important uses of Census data include the distribution of funds for government programs such as Medicaid; planning the right locations for schools, roads, and other public facilities; helping real estate agents and potential residents learn about a neighborhood; and identifying trends over time that can help predict future needs. Most Census data are available for many levels of geography, including states, counties, cities and towns, ZIP codes, census tracts and blocks, and much more.