The U.S. Census, which counts every resident in the country, happens every ten years. This incredible feat of mobilization and coordination, which has been happening every decade since 1790, is required by the U.S. Constitution. The data is used, among other things, to determine proportional representation in Congress.

There have been 22 federal censuses since 1790, with the most recent underway in 2020. Each U.S. Census provides a national snapshot of life across America in that year—a rich trove of information for anyone looking to learn more about our collective past as well as individual family members.

The data is released publicly 72 years after the census year. So the most recent publicly accessible U.S. Census records are from the 1940 Census. The next release of U.S. Census records, from the 1950 Census, is scheduled for 2022.

Collecting the Data: the Origins of the U.S. Census Bureau

U.S. Marshals and their assistants collected the data for the first nine censuses. The job became more daunting as the population grew, so in 1880 the country turned over the task to specially-trained enumerators, or census takers. According to the U.S. Census Bureau, "These people came from the communities that they counted and as such, reflected our growing nation.”

In 1840, a central office known as the Census Office was established. In 1902, a permanent Census Office was created. And in 1903 it was renamed the Census Bureau, and placed under the new-at-the-time Department of Commerce and Labor.

Today the Census Bureau is part of the Department of Commerce. It plans the decennial population censuses in advance and gathers valuable data about the American people and its economy through other censuses and surveys. It also hires temporary employees—up to 500,000 for the 2020 Census—to conduct interviews and process forms.

The Power of Census Data

Data from the U.S. Census is used to apportion, or distribute, seats in the House of Representatives to each state based on population. ­­­Census data also helps define  important areas of government like legislative districts and school districts. Local governments use census data to make important decisions like how many firefighters an area needs or where to build new schools, roads, and other public sector investments. The Census is also useful for developers and businesses, helping them choose where to build housing, establish factories, or open stores.

The Census also helps the federal government decide how to distribute hundreds of billions of dollars in funds per year to local, state, and tribal governments. These funds are allocated to communities for vital public infrastructure and services based on data collected in the Census, such as population totals and demographics.

Censuses can ask different questions every year, often reflecting the concerns of the period. Early instances of the U.S. Census just focused on population. But as policymakers and business leaders recognized the value of demographic data, the questionnaire got more involved. In 1880 for instance, the Census asked 26 questions about everything from marital status to literacy.

Here’s a quick look at the types of information collected by the U.S. Census over the years.

1790 to 1840

Early versions of the U.S. Census were pretty basic in that they included few questions. They asked for the name of the head of the household and just headcounts for everyone else. This was during the era of slavery, so the records listed the number of free White men and women and the number of enslaved individuals. And sometimes they recorded the town or district. At the time, this was all the federal government deemed they needed to determine Congressional representation and tax collection.

1850 to 1880

The Census questionnaire expanded significantly in the mid-19th century. In 1850, it started asking key demographic information of everyone in the home: name, age, sex, race, birthplace, occupation, education, and literacy. The 1880 Census also asked for respondents' relationship to the head of the household and their parents' birthplaces.

There were also specialized censuses during these years. Non-population schedules go into granular detail about farms and manufacturers. You can find out how many pigs and cows a person owned, how many pounds of butter they produced, or the value of a factory's machinery.

Slavery persisted in the U.S. until the 1860s. In 1850 and 1860, the Census recorded enslaved people separately in what were called slave schedules. Unfortunately, these records usually don't include names, but they do give age and gender. Although slave schedules  might support a hypothesis, on their own they rarely provide conclusive evidence as to who the enslaved person is on the schedule.

Mortality schedules from this time period list people who died in the year before the Census, and include not only details like cause of death, but more importantly for family history research, biographical details like name, age, and place of birth.

1890

This U.S. Census exists only as a fragment. Almost all of the records were destroyed in the aftermath of a fire at the Commerce Department in 1921. Only records for 6,160 out of 62.9 million people survived. The 1890 Veterans Schedules offer a partial substitute for ancestors who served in the Civil War, if you have Union ancestors who fought in the Civil War. It tallied surviving soldiers, sailors, and marines, as well as widows.

1900 to 1920

The U.S. Census became more detailed in the early 20th century, including street names and whether people owned or rented their homes. It added questions about naturalization status, immigration year, and native language. The 1900 Census included the number of children a woman had given birth to; in 1910 it asked if residents were Civil War veterans; and in 1920 it asked the year immigrant respondents became a U.S. citizen.

1930

The 1930 Census included several new categories: home value or monthly rent; age at a married individual’s first marriage; and whether someone was a veteran of the Civil War, Spanish American War, or World War I. It also asked whether people owned a radio, reflecting a new interest in consumer goods and mass communication.

The 1940 U.S. Census

The 1940 Census is the most recent one that is publicly accessible. It showed that the population was 132,164,569—a 7.3 percent increase from 1930. At the time nearly nine percent of Americans (11.6 million) were foreign-born; Italy, Germany, Russia, Poland, and England were the top five foreign countries listed as a birthplace.

It's a particularly compelling record, which captured a snapshot of the country as it emerged from the Great Depression. Concerned about the economy, the 1940 Census asked residents their income for the first time, as well as how many weeks they worked in 1939, and if they had income from sources besides work.

It covered occupation, income, employment status, education, homeownership, the value of a home or monthly rent, and where people were in 1935—and in some cases veteran status, native language, and parents' birthplaces.

All of these rich details, along with the fact that almost 9 out of 10 people living in the United States have a relative listed in the 1940 Census, make it a treasure trove for family history researchers. And it’s free to search on Ancestry®.

Census Innovation Through the Decades

Collecting so many details is a feat itself; tabulating everything is another. It took almost a decade to complete the count for the 1880 Census. A former Census Office employee invented a system that fed punch cards into an electronic counting machine system. This sped things up for 1890, but it still took several years to tabulate.

A number of innovations in the collection and tabulation of census data were introduced over the years. One example is statistical sampling—where enumerators could ask a small subset of the population extra questions, gathering more detailed insights about the state of the nation without increasing the burden on census takers (or adding as significantly to the cost). It was used in a decennial census for the first time in the 1940 Census.

Another example of technological innovation is the use of the first commercial electronic computers to analyze data from the 1950 Census. Census-by-mail was first used in the 1960 Census. And the 2020 Census is the first decennial U.S. census to not use paper for field work and offer a fully online option.

What You Can Discover in U.S. Census Records

The U.S. Census is a vital resource for genealogists. It includes key facts about your ancestors: name, age, residence, birthplace, marital status, occupation, and education. Census records give you a snapshot of your family in a given census year and, when used with other records, how your family evolved over the decades.

For instance a prosperous family of haberdashers in 1860 Boston could have looked very different in 1870, after the Civil War devastated the nation. A well-to-do merchant in 1920 may have been in a very different situation in 1930, after the Great Depression struck.

In addition to stories of your ancestors triumphing over adversity, you can also catch glimpses of milestones and success stories in the making. You can for instance find the first members of your family to own their own homes. You might even come across famous examples, like this 1880 Census record showing Thomas A. Edison, one of the greatest American inventors, as an Ohio-born scientist living in New Jersey, with his wife Mary and their three children. That same year he went on to found the Edison Illuminating Company, which later became General Electric.

The U.S. Census is also filled with rich details about your ancestors’ everyday lives. Since 1850, it asked residents their occupation, so you might discover an ancestor who was a rat catcher, clown, cowboy, or a soda jerk. Some listed their occupation as "gentleman" or "lady." You'll find celebrities, too, like Franklin D. Roosevelt (whose job was "president of U.S.A.") or an 18-year-old Walt Disney when he was an "artist cartoonist." You can see how much money people made, how many pigs they owned, and how old people were when they first married. Each U.S. Census can reveal something different about your family members.

What could you discover about your family? The best place to start is the 1940 Census and work backward through time. Begin your search on Ancestry today.

References

Census History Staff. "U.S. Census Bureau History: The Manhattan Project.” U.S. Census Bureau, July 1, 2020. https://www.census.gov/history/ (accessed July 2, 2020).