Boston Public Library
Decennial Census Information
Goverment Documents

The decennial census is the only data gathering operation in the United States that is mandated by the Constitution. The first census was taken in 1790 and it occurs every 10 years, in the years ending in "0". Its primary purpose is to provide the population counts that determine how seats in the U.S. House of Representatives are apportioned. Census figures also are required to draw congressional and state legislative district boundaries, to allocate federal and state funds, to formulate public policy, and to assist with planning and decision making in the private sector.