Individual-level records from the 1940 Census have been released by the National Archives for the first time, unlocking a digital treasure chest for people researching their family histories. When records were made available on April 2, demand was so great that the website was paralyzed, according to media accounts.

The records were released by the National Archives and Records Administration, under a federal law that protects individual-level records for 72 years after the census is taken. The law, passed in 1978, was an outgrowth of an agreement between the Census Bureau and National Archives in 1952.

The 1940 Census counted 132.2 million Americans. As is the case today, it showed more rapid growth in the West and the South than in the Midwest and Northeast. Its population statistics found no cities of 500,000 or more between St. Louis and California; now there are a dozen such cities in the Southwest and Mountain West.

The census tallied a nation that was 89.8% white, and there was no census category at the time for Hispanics (it was not added to all census forms until 1980). A quarter of adults ages 25 and older had at least a high school diploma, compared with 86% today. Only 44% of households owned their own homes, compared with 65% in 2010.

How Census Was Taken

The 1940 Census was taken in April of that year entirely by enumerators who went door-to-door and recorded people’s answers to their questions. The 1940 Census was the first to ask some questions of a random sample of the population, which was a way to gather more information about conditions during the Great Depression without burdening all respondents.

Among the new questions added to the census form were those about earned income, other income, Social Security receipt, and place of residence five years ago. Also added were questions about the age or date of first marriage, and whether someone had been married more than once.

A housing census, conducted at the same time, asked questions about the type of structure, condition, year built, plumbing and kitchen facilities, costs and other information. The housing census forms were destroyed and are not included in the release of 1940 Census material.

For the time being, records can only be searched by address or location, but efforts are underway to make them searchable by name.

The 1940 Census records are organized by enumeration districts (although there are separate pages for people living in places such as hotel tourist homes or trailer camps). For people hoping to look up their family members, it is helpful to have the correct street address. The National Archives site also provides maps to help people find the correct enumeration district.

According to an FAQ page provided by the National Archives, a community volunteer project is underway to make the 1940 Census searchable by name. Private genealogy organizations also are working to add name-indexed census records to their websites.

Why 72 years?

The negotiations between the two agencies followed passage of a law in 1950 that National Archives officials interpreted as allowing release of census records 50 years after the census was taken. Census Bureau officials countered by proposing a 72-year waiting period.

That time span seemed to offer a reasonable protection of people’s privacy, while offering research opportunities to social scientists and people looking up family history. The usual explanation for why the agencies agreed on 72 years was that it was about the same as the average lifespan at the time (, Table 21), although documentation for this is sparse.

Other resources:

Census Bureau page on the 1940 Census:

National Archives site with access to 1940 Census: