What is the Decennial Census?
The federal government conducts a full count of the US population every ten years, starting in 1790. Questions change every decade, but there is always some information about every individual in every household as well as some information about housing conditions.
Decennial Census data is available from a variety of sources and comes as aggregated (or summary) totals or microdata.
Aggregated data are totals by subject (such as race or age) and geography and microdata refers to individual survey responses.
Aggregated Data
There are many sources for Decennial Census data. Here are a few that we recommend:
For researchers in a hurry:
For detailed information and tables:
National Historical GIS (For historical and longitudinal research)
Microdata
Data.census.gov also has a microdata portal in beta version
Nerd Section
Decennial Census data is available from a variety of resources, however you may want to consult the Technical documentation for the Census, including the survey instruments and questionnaires for all censuses since 1790.