Population Research

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.

• Census 2020 - For the latest information on the 2020 Decennial census.
• Librarian's Pick Social Explorer - User-friendly interface for interactive maps and census data reports from 1790 to the present. Also includes the 2011 censuses for Canada and the United Kingdom.
• Data.census.gov - Data by topic, census profiles, mapping and tables.  (Advanced Search Recommended.)  For information about particular groups such as African Americans, American Indians and Alaska Natives, Hispanics, Asian Americans and Native American and Other Pacific Islanders, see Data Links.
• Annual Intercensal Estimates for the nation, states, counties and some cities and towns. 1909 - .
• U.S. Census Quickfacts - Current population and other data for locations with a population of 5,000 or more. Options for viewing the data in charts, maps or tables.
• IPUMS Abacus - Beta product that provides the ability to create frequency tables and crosstabulations, and also compare across two time points. Limited to a maximum of two variables and two time points for a single tabulation. Generates a link to share tables. 
• U.S. State Data Center Program - A network of Data Centers  that provide census information
• U.S. Population Projections - Census Bureau estimates of the population for future dates.
• PolicyMap - Online data and mapping application providing access to housing, crime, mortgage, health, demographic, job, and education indicators from both public and proprietary sources. Geographic availability differs by source. Some data available for downloading.
• Census Survey Explorer – Discover U.S. Census Bureau surveys or censuses by filtering and searching by geography, frequency, topics, and subtopics.
• For assistance with using U.S. census microdata from the sources below, contact the Data and Statistical Services consultants.
• IPUMS USA - University of Minnesota - Harmonized U.S. census microdata with enhanced documentation. Data includes decennial censuses from 1790 to 2010 and American Community Surveys (ACS) from 2000 to the present.  Data can be downloaded in compressed format, and recoding permits users to compare various years.
• ICPSR - Provides raw data files for manipulation and analysis. Browse from https://census.icpsr.umich.edu/census/search/studies, Census Enumerations: Historical and Contemporary Population Characteristics.

For detailed historical census information (including individual census records) see the Historical U.S. Census and Vital Records guide.

• U.S. Census Published Volumes - PDF versions of published U.S. Census publications. 1790-2010. Available via IPUMS.
• Decennial Census of Population and Housing by Decades follows the evolution of the decennial census by detailing the events surrounding each of them.  
• Historical Statistics of the United States. Millennial ed. Carter, S. B.  New York: Cambridge University Press, 2006. Wide range of historical data. Tables cover specific indicators such as employment, income, saving, poverty, construction, housing, consumer price indexes, and others.
• Population Information in Nineteenth Century Census Volumes Shulze, S. Phoenix, AZ : Oryx Press, 1983. Identifies the population information in the U.S. Census decennial reports from 1790 to 1890. Describes the contents and unique aspects of each census.
• Population Information in Twentieth Century Census Volumes: 1900-1940  Shulze, S. Phoenix, AZ : Oryx Press, 1985
• Population Information in Twentieth Century Census Volumes: 1950-1980 Shulze, S. Phoenix, AZ : Oryx Press, 1988
• Bibliography and Reel Index: A Guide to the Microfilm Ed. of the U.S. Decennial Census Publications, 1790-1970 Woodbridge, Conn. : Research Publications, 1975. Serves as a bibliography of U.S. Decennial Census Publications for 1790-1970 and as a reel index for the microform collection. Includes statistics on race, nationality, sex, occupations, and education. 
• Censuses of U.S. Native Americans – U.S. Census Bureau history of the census counts of American Indians as defined by the U.S. government. . 

• Decennial Census of Population and Housing Questionnaires and Instructions 1790-2020 
• Index of Census Questions 1790-2010
• Measuring Race and Ethnicity Across the Decades 1790-2010 - Timeline of changes to how the U.S. census counted race and ethnicity