Decennial census mandated by Article I, Section 2 of the United States Constitution
The United States census is a census that is legally mandated by the Constitution of the United States. It takes place every ten years. The first census after the American Revolution was taken in 1790 under Secretary of State Thomas Jefferson. There have been 23 federal censuses since that time. The census includes territories of the United States. The United States Census Bureau is responsible fo... Wikipedia