If you are looking for ancestors who were born in or emigrated to the United States, US Census records are one of your most valuable tools. They don’t provide precise records of births, marriages, or deaths, but they offer a wealth of clues to these events and valuable information as to where and how ancestors lived.
Every 10 years since 1790, the US government has conducted a nationwide census. Officially, the census’s purpose is to insure each state, based on its population, an equitable allocation of seats in the US House of Representatives (US Constitution, Article I, Section 2). But the census does more than just count heads. The government also gathers other information from each person and household — in fact, a slightly different set of information in each census. This data facilitates various types of research by government, businesses, and other entities. Family historians use it to find ancestors, discover where they lived and when, and to gather clues for further research.
The US Census Bureau publishes many different kinds of information, based on the latest census, but, to protect privacy, the actual census records are not released until 72 years after the census. So the 1940 US Census was released in 2012. (This 72-year rule has not always been in place; see below.)
Here’s a quick survey of the US Censuses which are already available, with notes about what was asked; the reported population; a few morsels of history, politics, and technology; and one big fire.
To see notes about a particular census, skip the proper heading below; they’re in chronological order. To see how the census evolved, start with 1790. If what you really want to do right now is search the censuses for your ancestors, follow this link to the WorldVitalRecords US Census collection.