United States census

The United States Census is a census done in the United States every ten years.  It is required by the United States Constitution which calls for a decennial census done in years ending in "0" since 1790. It is actually two census counts taken concurrently (at the same time). The first is the census of the population, taken from 1790 to the present. The second is the census of housing, which counts the number of residential housing units, and was taken from 1940 to the present. Among other uses, the count is used to determine how many places in the House of Representatives each state has.  It also determines how much government money is spent in different locations. 

The United States Census Bureau is responsible for the United States Census.  The first census after the American Revolution was in 1790.  Secretary of State Thomas Jefferson was responsible for this first census.

References

Other websites
 U.S. Census Bureau official website