Today, the fundamental purpose of conducting the census continues to be legislative reapportionment and redistricting. The census is conducted every ten years and in 2000 counted 281.4 million U.S. residents. The Bureau of the Census conducts many nationwide surveys throughout the decade to supplement and update decennial census data. As the population grew and fewer people were home during the day, it became more efficient to conduct the census by mail. The 1970 Census was the first in which forms were mailed to homes in certain parts of the country.
All households receive a questionnaire containing seven basic population and housing questions.