An estimated 87 percent of Americans today can connect with at least one relative in the 1940 United States Federal Census—currently the largest census released to date and the most recent census available for public access.

Historical Background

Since 1790, the federal government has taken a census every 10 years to determine how members of the House of Representatives are apportioned. The U.S. census taken on 1 April 1940 was the 16th census of the United States. It tallied the population of the country at 131,669,275 for the continental U.S. This represented an increase of 7.2 percent for the continental U.S. since the 1930 census. Adding Hawaii, Alaska, Puerto Rico, Guam, the U.S. Virgin Islands, American Samoa, and the Panama Canal Zone (all included in this database) brought the total to 134,176,298.

To facilitate the count, census planners divided the country into enumeration districts. These were geographic areas designed to allow a census taker (enumerator) to visit every house in the district within a two-week period (in rural areas, enumerators had a month). Enumerators were instructed to “visit every house, building, tent, cabin, hut, or other place in which any person might live or stay, to insure that no person is omitted from the enumeration” and to count “each person alive at the beginning of the census day, i.e., 12:01 A.M. on April 1, 1940.”

Census enumerators wrote "Ab" after names of people who belonged to the household but were absent on April 1. Visitors were to be counted as members of the household at their normal place of residence, as were students, patients at hospitals and sanitariums who had a permanent home, and servants and household employees who did not sleep on the premises.

Because the official cutoff for the census was 12:01 a.m. on April 1, babies born later that day should not have been included. Residents of “hotels, tourist or trailer camps, missions, and cheap one-night lodging houses (flophouses)” were enumerated based on where they spent the night on 8 April 1940. Enumerators worked throughout the month and into May finishing the count.

What You May Find in the Records

Enumerators recorded answers for the following questions on the 1940 census:

address

home value and whether owned or rented

name of each person whose usual place of residence on 1 April 1940 would be in the household

relationship to head of household

sex

color or race

age at last birthday

marital status

education

place of birth

citizenship

residence on 1 April 1935

employment status for those 14 and older (several questions)

occupation and number of weeks worked full-time in 1939

income in 1939

Enumerators also asked supplementary questions to provide a random sample of about 5 percent of the population. These questions included

birthplace of mother and father,

native language,

veteran status (including widow or minor child of a veteran),

Social Security details,

occupation, industry, and class of worker,

marriage information for women (married more than once, age at first marriage, number of children).

Interesting Facts

The top five foreign countries listed as a birthplace were Italy, Germany, Russia, Poland, and England.

New York was the most commonly listed birth state.

The average household size enumerated in the 1940 census was 3.7 people.

Two women tied for the oldest person in the census: both Mary Dilworth of Oxford, Mississippi, and Cándido Vega Y Torres of Guayama, Puerto Rico, listed their ages as 119.

Mary and John were the most common given names appearing in the 1940 census.

The top five surnames in the 1940 census were Smith, Johnson, Brown, Williams, and Jones.

More than 850,000 people reported living in hotels or similar housing.

Search Tips

Census records make a great starting place for getting to know your family. You can find a guide to using census records in your research here.

The census contains great information, but some data may not be completely accurate. For example, individuals may not have known the answers to certain questions; the census taker may have asked a neighbor for information if the family could not be contacted; and people did not always give truthful information. Be prepared to corroborate information you find in the census with other records.

If you encounter illegible writing, study the handwriting of the enumerator. You can do this by picking out the most legible letters and words on the page and working from there. For example, the enumerator listing Abraham Lincoln in the 1860 census (Illinois) wrote the letter "L" in a way that resembles an "S". Without looking at other words on the page, one might think that Lincoln was a "Sawyer" instead of a "Lawyer."