The US Constitution requires it take place every 10 years. "The actual enumeration shall be made within three years after the first meeting of the Congress of the United States, and within every subsequent term of 10 years, in such manner as they shall by Law direct." - Article I, Section 2 of the Constitution of the United States.
The decennial census results determine how taxpayer money is spent on emergency services, hospitals, job training centers, schools, senior centers, bridges and other public works projects.
The data collected by the census helps determine the number of seats states have in the US House of Representatives.
The Commonwealth of Puerto Rico is included in the census.
1840 - Questions are added about education, vocation and industry.
1850 - Detailed information about all household members, white and non-white, is collected for the first time. Additional information on taxes, schools, crime, wages and data on mortality is collected.
1890 - First census in which the electric tabulation system is used.
The Census Bureau's 1910 population and economic data is used during the nation's mobilization for World War I
Census Bureau creates the first "long form," which asks additional questions
and is only completed by a subset of the population.
1950 - The first non-military computer, UNIVAC, is used to tabulate the 1950 census.
For the first time, residents self-identify their race.
1970 - The Census Bureau is asked by people of Hispanic descent to be able to identify themselves as such.
1980 - Following the 1980 count, 54 lawsuits, many by civil rights groups, are filed against the Census Bureau for improper and unconstitutional methods of counting.
2000 - The first advertising campaign used to promote the census costs $167 million. The Census Bureau calculates the population to be 281,421,906. People can mark more than one race, and a "some other race" category is also included.
March 2010 - Census forms are mailed or delivered to households.
April 1, 2010 - National Census Day is promoted as the day to return completed forms.
April-July 2010 - Census takers visit households that have not returned their completed forms.
December 14, 2010 -
2005-2009 American Community Survey
five-year estimates are released. This marks the first release of five-year estimates. The American Community Survey includes "social, economic, housing and demographic statistics for every community in the nation."
December 31, 2010 - The Census Bureau is required by law to deliver population information to the president for apportionment.
August 8, 2013 - John H. Thompson is sworn in as the director of the US Census Bureau.