Beginning in 1790, the United States has conducted one national census every ten years. In an effort to provide detailed information more frequently, beginning in 2005, the Census Bureau also began conducting the nationwide American Community Survey (ACS) to collect data on a broad range of subjects on a regular basis. This survey was designed to supplement the brief “short form” decennial census which is still administered. The ACS has an annual sample size of about 3.5 million addresses, with survey information collected nearly every day of the year. Data are pooled across a calendar year to produce estimates for that year. As a result, ACS estimates reflect data that have been collected over a period of time rather than for a single point in time as in the decennial census.
Estimates of ACS data are available on an annual* and five-year basis, depending upon the population size of the geographic area. Special caution must be used when comparing data over time. For more information, see Understanding and Using American Community Survey Data: What all Data Users Need to Know; and ACS Guidance for Data Users.
* Note, the Census Bureau did not release standard ACS 1-year data for 2020 due to the impacts of the COVID pandemic on data collection. The Census Bureau released experimental estimates from the 2020 ACS 1-year data.
For detailed historical census information (including individual census records) see the Historical U.S. Census and Vital Records guide.