The 2010 United States Census (commonly referred to as the 2010 Census) is the twenty-third and most recent United States national census. National Census Day, the reference day used for the census, was April 1, 2010. The census was taken via mail-in citizen self-reporting, with enumerators serving to spot-check randomly selected neighborhoods and communities. As part of a drive to increase the count's accuracy, 635,000 temporary enumerators were hired. The population of the United States was counted as 308,745,538, a 9.7% increase from the 2000 Census.
As required by the United States Constitution, the U.S. census has been conducted every 10 years since 1790. The 2000 U.S. Census was the previous census completed. Participation in the U.S. Census is required by law in Title 13 of the United States Code.
On January 25, 2010, Census Bureau Director Robert Groves personally inaugurated the 2010 Census enumeration by counting World War II veteran Clifton Jackson, a resident of Noorvik, Alaska. More than 120 million census forms were delivered by the U.S. Post Office beginning March 15, 2010. The number of forms mailed out or hand-delivered by the Census Bureau was approximately 134 million on April 1, 2010. Although the questionnaire used April 1, 2010 as the reference date as to where a person was living, an insert dated March 15, 2010 included the following printed in bold type: "Please complete and mail back the enclosed census form today."
The 2010 Census national mail participation rate was 74%. From April through July 2010, census takers visited households that did not return a form, an operation called "non-response follow-up" (NRFU).
The Census Bureau did not use a long form for the 2010 Census. In several previous censuses, one in six households received this long form, which asked for detailed social and economic information. The 2010 Census used only a short form asking ten basic questions: