The 1940 U.S. Census was the 16th federal population count. It captured details about Americans’ lives as of April 1, 1940. Franklin D Roosevelt was in his second term as U.S. President, and the U.S. was just emerging from the Great Depression.

If you, like many Americans, have a relative who was living in the U.S. in 1940, this census is a valuable resource for discovering details about your family at a historically fascinating time. You’ll get a snapshot of their lives as they watched the early months of World War II unfold across the sea in Europe—and less than two years before America too would enter the war.

What Was the Population of the United States in 1940?

The U.S. Census determined the population of the United States in 1940 to be 132,164,569 people, an approximately seven percent increase from the previous census in 1930. Nearly nine percent of Americans (11.6 million) were foreign-born. Turn-of-the-century immigration consisted of people coming mostly from Eastern and Southern Europe. Among the top countries listed as a birthplace by people in the 1940 Census were Russia, Poland, Italy, and Hungary, as well as Germany and England.

The 1940 Census marked the first time that every state had a population of 100,000 people or more. Nevada, home to 110,000 residents, was the least populous state in the union. And New York, with 13.5 million people, was the most populous state.

As for the biggest cities in terms of population, New York City was the country’s largest, retaining the top spot from the previous census in 1930. The second and third biggest American cities were Chicago and Philadelphia.

What 1940 Census Records Can Reveal About Your Ancestors

Census records are a valuable resource for family historians. Census takers, or enumerators, did more than count heads. They asked a wide range of questions that can bring your ancestors’ stories to life.

The 1940 Census was the first to incorporate statistical sampling. It asked a small, random sample of the population extra questions from which it could extrapolate data for the whole country. This longer form asked respondents their parents' birthplaces, native language, age at first marriage, and veteran status. It noted if someone fought in World War I, the Spanish-American War, or the Philippine-American War, or if they were the child or widow of a soldier.

There's rich information about the rest of the population too. Enumerators asked all respondents their age, race, marital status, occupation, and their monthly rent or home value. The 1940 Census was also the first to ask about education level. Interestingly, only five percent of Americans had a bachelor's degree or higher.

In addition to listing a person’s address in 1940, the 1940 Census also noted a person’s address in 1935. This means the 1940 Census could give you insights into how the Great Depression affected your family. For instance, if you see them listed in the census with a Midwest address in 1935 and then listed with an address on the West Coast in 1940, this could be an indication of hardships like the Dust Bowl propelling your ancestors westward, leaving behind the drought-stricken Midwest region.

The 1940 Census also asked if respondents had participated in the Works Progress Administration (WPA), a program that put about 8.5 million people to work at a time when they so needed a job. It resulted in many of the iconic buildings and landmarks we have today such as the Hoover Dam and the Library of Congress.

And the variety of WPA jobs your ancestors may have participated in is fascinating as well: In addition to infrastructure jobs, the WPA had forestry jobs, women’s sewing projects, and projects for artists, such as the Federal Writers Project in which writers collected firsthand accounts from formerly enslaved people in the South.

The 1940 Census also recorded how many weeks people worked in 1939 and their earnings that year. It found that the median annual income was $956 for men (about $18,000 today) and $592 for women ($11,200).

Tips for Searching 1940 U.S. Census Records on Ancestry^®

Most Americans can connect with at least one relative in the 1940 U.S. Census, which contains records for all 50 states and territories, plus Puerto Rico, the Virgin Islands, Guam, American Samoa, and the Panama Canal Zone. It's the most recent census available for public access until the 1950 Census is released in 2022.

Here are some tips for searching the 1940 Census records on Ancestry^® to discover more of the rich details of your family’s past.

Make sure the location where your family is listed makes sense. Historically, Americans lived in the same area for decades. But between 1935 and 1940, according to census statistics, over 7 million people migrated within the country. They usually moved near family or people with similar ethnic backgrounds; so if your family shows up in a surprising location, double check that you have the right people.

Search for your family in other censuses and vital records. A lot can happen in a decade—especially when it includes the Depression years. You can get a sense of how they weathered the crisis by comparing their answers in the 1940 Census with the 1930 Census, such as monthly rent or home value and unemployment status. Birth, marriage, and death records—known as vital records—can help fill in the details of the intervening years, like where someone died, married, or had a child.

The 1940 Census could lead you to learn more about veterans in your family. If the census includes a man between about 15 and 40 years old, he may have later fought in World War II. You can search military records like draft registration cards to find out.

Look at children's ages for other clues about the family's life. If there's a large age gap between children, they may have lost a sibling. The infant mortality rate was still high in 1940: 47 in 1,000 births, versus about 5 in 1,000 today. Also note where the eldest child was born, because it could be a clue to where the parents married.

Keep an eye out for unusual occupations in the family. Many people have farmers and laborers in their family tree, but you might luck out and find an ancestor who worked as an ice cutter, lamplighter, rat catcher—or even a clown. This can make them easier to identify in other censuses.

Remember that some data may not be completely accurate. If no one was home, the census taker may have asked a neighbor for information. The person next door could have the facts wrong, mistaking Portland, Oregon for Portland, Maine, for example. Always confirm information in other censuses or vital records.

Study the census taker's handwriting if it's hard to read. Loopy, indecipherable script is typical of historical documents like the census. But you can learn to read the census taker's handwriting. Find the most legible words on the page and make some educated guesses: A "sawyer" listed under occupation probably says "lawyer," but with an L that resembles an S.

Explore your family story in the 1940 Census

The 1940 Census offers a window into your family's life at a momentous time in history, showing where they stood after the Depression and on the cusp of World War II. Discover your family story in the 1940 Census today.

References

"America’s Foreign Born in the Last 50 Years." U.S. Census Bureau. Accessed June 9, 2021. https://www.census.gov/content/dam/Census/library/visualizations/2013/comm/foreign-born.pdf.

"Developing Sampling Techniques." U.S. Census Bureau, 2010. https://www.census.gov/history/www/innovations/data_collection/developing_sampling_techniques.html.

History.com Editors. "Dust Bowl." History.com, October 27, 2009. https://www.history.com/topics/great-depression/dust-bowl. "Infant Mortality." Centers for Disease Control and Prevention. Accessed June 9, 2021. https://www.cdc.gov/reproductivehealth/maternalinfanthealth/infantmortality.htm.

Malloryk. "'It's Your America:' The 1940 Census Today." The National WWII Museum | New Orleans, May 21, 2020. https://www.nationalww2museum.org/war/articles/1940-united-states-census.

"Pop Culture: 1940." U.S. Census Bureau. Accessed June 9, 2021. https://www.census.gov/history/www/through_the_decades/fast_facts/1940_fast_facts.html.

Potter, Constance. "New Questions in the 1940 Census." U.S. National Archives and Records Administration, 2010. https://www.archives.gov/publications/prologue/2010/winter/1940-census.html.

"Profile America Facts for Features: *Special Edition* 1940 Census Records Release." U.S. Census Bureau, February 22, 2012. https://www.census.gov/newsroom/releases/archives/facts_for_features_special_editions/cb12-ffse01.html.

"QuickStats: Infant, Neonatal, and Postneonatal Annual Mortality Rates* --- United States, 1940--2005." Centers for Disease Control and Prevention. Accessed June 9, 2021. https://www.cdc.gov/mmwr/preview/mmwrhtml/mm5714a6.htm

"Sources of Recovery." Encyclopædia Britannica. Accessed June 9, 2021. https://www.britannica.com/event/Great-Depression/Sources-of-recovery.

"Works Progress Administration." Wikipedia. Accessed June 9, 2021. https://en.wikipedia.org/wiki/Works_Progress_Administration.