Every 10 years, the U.S. Census Bureau conducts a census to count every resident in the United States. The census is conducted in years ending in zero, and the reference day for the next census will be April 1, 2020 ─ Census Day! In 2020, we are providing three modes of response so everyone will be able to respond the way they prefer: either anytime, anywhere through the Internet, or over the phone or by returning a paper questionnaire.
The data collected by the decennial census are used to determine the number of seats each state has in the U.S. House of Representatives. The first U.S. census was in 1790 during the first term of our first president, George Washington. Secretary of State Thomas Jefferson led the effort. The population counted was 3,929,625. Congress used these results to apportion 105 seats among the 15 states.
Source: Vintage 2018 Population Estimates.
From the 2020 Census:
More information about the Decennial Census Program.
The Decennial Census and the American Community Survey (ACS) are part of the Decennial Census Program of the Census Bureau. Since 2005, in order to provide communities, businesses and the public with detailed information more frequently, data that were historically collected only once every 10 years by the decennial census long form have been collected monthly (and released annually) through the ACS.