What’s in a US Census?

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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.

1790 US Census page

A page from the 1790 US Census

1790: The First Census

The 1790 US Census recorded the name of each head of household, but only the numbers of other persons in the household, including these categories:

  • free white males 16 years and up (to assess military and economical potential)
  • free white males under 16 years
  • free white females
  • all other free persons
  • slaves

Completed census lists (schedules) were posted in public places in each community for inspection. People in the 13 original states were counted, plus Kentucky, Maine, Vermont, and the Southwest Territory (Tennessee).

According to this census, the US population was 3,929,326.

1800: The Second Census

The 1800 US Census categorized household members into age groups, but heads of households were still the only persons whose names were recorded. This census included new territories to the northwest of the original states.

According to this census the US Population was 5,308,483, up 35.1% from 1790.

1810: The Third Census

Census takers in the 1810 US Census were required to collection economic data — specifically, about manufacturing — in addition to demographic data. However, there was no standard form for collecting this data, so it was quite erratic and mostly useless.

According to this census, the US Population was 7,239,881, up 36.4% from 1800.

1820: The Fourth Census

For the first time, the 1820 US Census asked if respondents were employed in agriculture, commerce, or manufacturing. Unfortunately, poor training of census-takers (enumerators) compromised the usefulness of this economic data.

According to this census, the US population was 9,638,453, up 33.1% from 1810.

1830: The Fifth Census

Previous censuses had begun in August, but the 1830 US Census began in June, at President Andrew Jackson’s recommendation. It included more detailed age information about household members, grouping them by age with intervals of ten years. This was the first census to use uniform printed “schedules” (forms). In previous censuses, local census marshals produced and bound their own forms. After two failures to collect good economic data (in 1810 and 1820), this census abandoned the effort and focused solely on counting the population.

According to this census, the US population was 12,866,020, up 33.5% from 1820.

1840: The Sixth Census

The 1840 US Census included new questions about school attendance, literacy, and occupation.

According to the 1840 Census, the US population was 17,069,453, up 32.7% from 1830.

1850: The Seventh Census

The 1850 Census included questions about mines, agriculture, commerce, manufacturing, and education, but the most significant innovation was including the names of all free persons, not just heads of household. Some information was also collected about taxes, wages, schools, crime, and property values.

According to this census, the US population was 23,191,876, up 35.9% from 1840.

1860: The Eighth Census

The 1860 Census used essentially the same questions as the 1850 Census, having been authorized by the same law in 1850.

According to this census, the US population was 31,443,321, up 35.6% from 1850.

1870: The Ninth Census

The 1870 Census was the first taken after the US Civil War and the emancipation of all slaves in the United States. Accordingly, it was the first US Census not to count slaves. For the first time, prospective census workers (enumerators) had to prove their qualifications by passing a test. The burden of tallying earlier censuses led the chief clerk of the Census Office, Charles W. Seaton, to invent a rudimentary tallying machine, which was used to count the 1870 census.

According to this census, the US population was 39,818,449, up 26.6% from 1860.

Mary C. Oursler, Official Custodian of Census Records, 1937

Mary C. Oursler, Official Custodian of Census Records, U.S. Census Bureau, 1937

1880: The Tenth Census

If no one was available at a household, 1880 Census enumerators were authorized to obtain the desired information about that household from its nearest neighbors. Data was also gathered about railroad corporations, telegraph companies, insurance companies, and some other businesses, and fines were authorized if any corporate officer refused to answer any of the questions asked. All untaxed Indians (Native Americans) within the United States were counted, as were the population and resources of Alaska, which would not become a state for several more decades.

As both the population and the census questionnaire grew, the task of tabulating the responses also grew. The 1880 Census took ten years to count.

According to this census, the US population was 50,189,209, up 26.1% from 1870.

1890: The Eleventh Census

The 1890 Census was the most detailed US Census to date, and more detailed than the next few. It asked about the ownership and indebtedness of homes and farms and gathered detailed information about surviving Union soldiers and sailors and their service, as well as the widows of deceased military personnel. A new question asked a person’s race. Married women were asked how many children they had borne and how many were still living. A separate sheet was used for each household’s census responses.

An electric tabulating system was used for the first time; it involved transferring data by hand from handwritten questionnaires to punch cards. Metal pins detected the holes punched in the cards and tabulated the results accordingly.

In 1921 most of the 1890 Census was destroyed in a fire, along with parts of some past censuses. For this story and a brief account of political intrigue involved in the 1890 Census, see Kellee Blake’s “First in the Path of the Firemen: The Fate of the 1890 Population Census.”

According to this census, the US population was 62,947,714, up 25.4% from 1880.

1900: The Twelfth Census

In authorizing the 1900 Census, Congress limited its scope to questions about population, mortality, agriculture, and manufacturing. Separate assessments were authorized on subjects ranging from deafness and blindness to juvenile delinquency, transportation, and religious organizations. Hawaii, which the US annexed in 1898, was included for the first time.

According to this census, the US population was 76,212,168, up 21.1% from 1890.

1910: The Thirteenth Census

The 1910 Census was begun in April instead of June at the suggestion of the head of the Census Bureau, who thought too many city-dwellers would be out of town for vacation during the summer. President Theodore Roosevelt insisted that the census-takers (enumerators) be hired through the civil service system for the first time. Traditionally, these had been patronage positions.

A month before the Census began, Congress required the addition of a question about the nationality or native language of foreign-born residents and their parents. The questionnaires had already been printed, so this information was added in the birthplace column of the forms.

According to this census, the US population was 92,228,496, up 21.0% from 1900.

1920 census taker

Taking the 1920 census.

1920: The Fourteenth Census

The 1920 Census began on January 1, 1920, at the request of the Department of Agriculture, which wanted information about the previous harvest to be fresh in farmers’ minds. This innovation did not continue; future censuses would begin on April 1.

The authorizing legislation for this census allowed persons to obtain copies of census records for genealogical research, on the condition that the information not be used to the detriment of the persons listed.

Past questions about the numbers of children born to mothers and how long couples had been married were omitted. Household members who were temporarily away were listed with the household. Enumerators were not authorized to request proof of any information, and individuals were not required to spell out their names. Race was determined by the enumerator’s observation.

Because of changes in some national boundaries in Europe after World War I, persons who reported being born in Austria-Hungary, Germany, Russia, or Turkey were also asked to report the province in which they were born.

Although the US Constitution provides for the decennial census as a means to apportion seats in the House of Representatives among the states, there was no reapportionment based on the 1920 Census. This is not because nothing had changed. In fact, the census showed a major, continuing shift of the US population from rural to urban areas. Fearful of losing power to the cities, representatives from rural districts managed to derail reapportionment legislation. When Congress finally passed a reapportionment bill in 1929, it directed that the next reapportionment be according to the 1930 Census. To avoid similar problems in the future, this legislation authorized automatic reapportionment based on future censuses.

According to this census, the US population was 106,021,537, up 15.0% from 1910.

1930: The Fifteenth Census

The 1930 Census followed shortly after the stock market crashes which began the Great Depression. Urgent needs for unemployment information led the Census Bureau to rush the publication of that data. Congress thought it to be inaccurate — too low — so it authorized a special unemployment census in January 1931. Another followed in 1937. The latter is interesting because it the data was gathered by postal carriers, and because this was the first time the Census Bureau experimented with statistical sampling. Two percent of households were given a special questionnaire, which was used to measure the accuracy of the complete census.

According to this census, the US population was 122,775,046, up 15.8% from 1920.

1940: The Sixteenth Census

The 1940 Census involved the use of sophisticated statistical techniques, not to determine the population, which would arguably be unconstitutional, but to allow the inclusion of additional questions without burdening the tabulation process, and also to allow the publication of preliminary returns several months before the complete results became available.

To assess the ongoing impact of the Great Depression, the 1940 Census added questions about income, employment, unemployment, and internal migration.

According to this census, the US population was 132,164,569, up 7.7% from 1930.

1950 and Beyond: Still Unavailable

Later censuses are still unavailable to the public. The 1950 Census will be released April 1, 2022, 72 years to the day after it began.

Meanwhile, here’s one thing we do know. Based on the 2010 US Census, the Census Bureau estimates the US population in 2010 at almost 309 million. The Bureau estimates that the population has grown to over 315 million since 2010.

Search the WorldVitalRecords US Census collection

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