The second census was managed by Secretary of State John Marshall and was completed in nine months.

The set of questions expanded to include the name of the head of family, a count of all free White people and their ages within a range and counts of all other free people (except “Indians, not taxed”) and slaves.

The marshals were required by law to display completed census questionnaires in two public places in each jurisdiction for respondents to make corrections.

• Kentucky and Tennessee had become states and their populations were counted.
• Population counts were taken in the District of Columbia, the Mississippi Territory and the territory Northwest of the Ohio River (which would become Indiana, Illinois, Michigan, Ohio, Wisconsin and part of Minnesota).

Congress feared shortages of finished goods from Europe due to Napoleon’s wars. It legislated that the next census collect and tabulate manufacturing data.

Enumerators had been given a virtually impossible task: conduct this first census of manufactures with little instruction, no training and no prescribed questions. Most experts found the resulting count of poor quality. 

Enumerators faced resistance to questions about business operations. In North Carolina, one reported that requests for data "created Jealousies in the minds of a Great Number of the people, consequently No Great reliance can be placed on the same.”

This was the last census to show Virginia as the most populous state.

The fourth census went through a major expansion, adding more age groups within the sex, race and enslaved categories. Secretary of State John Quincy Adams oversaw the effort, which took about 13 months to complete.

This was the last census to use forms hand-drawn by the enumerators.

Just like in 1810, the manufacturing data was of poor quality.

• The Arkansas and Missouri territories were counted.
• Asked questions about naturalization and the “numbers of persons engaged in agriculture, commerce, and manufacturing.”
• New York, Pennsylvania and Virginia populations exceeded 1 million.

The sixth census, the last under the purview of the secretary of state, once again collected economic data, this time asking for the number of people in each family employed in these industries:

• Mining.
• Agriculture.
• Commerce.
• Manufactures and trades.
• Navigation of the ocean.
• Navigation of canals, lakes, and rivers,
• “Learned professions” and engineers.

The nation’s seventh census was the first under the U.S. Census Board, which consisted of the secretary of state, attorney general and postmaster general.

Once again, U.S. marshals collected the information. Congress moved responsibility for tabulating and reporting to the newly created Department of the Interior.

The census showed the U.S. population surpassed that of the United Kingdom for the first time.

The nation’s ninth census took place five years after the Civil War ended. No longer collecting data for the “slave questionnaire,” this census provided the first detailed information on the Black population after slavery was abolished.

This census saw the introduction of official maps and figures on its most significant findings and a simple tallying device, invented by future Census Superintendent Charles W. Seaton, was employed to assist tabulation.

This was the last census collected by the U.S. marshals.

The prior census took nearly a decade to tabulate. Worried future reports would take even longer, the federal government held a contest to encourage creation of speedier methods.

A former Census Bureau statistician, Herman Hollerith, invented an electric counting machine that utilized punch cards to tally respondents’ characteristics, revolutionizing census tabulation. His company would later become International Business Machines, better known as IBM.

Nearly all records from the 1890 Census were destroyed in a 1921 fire at the Department of Commerce building.

Although the 1880 and 1890 Censuses furnished large quantities of statistics, they took too long to tabulate (even with the advent of the Hollerith machine), failing to provide information when it was most needed. Consequently, Congress limited the 1900 Census to questions on population, manufacturing, agriculture and mortality.

Telephone inventor Alexander Graham Bell was appointed “expert special agent of the Census Office for the preparation of the Report on the Deaf and the Blind” for the 1900 Census.

• Hawaii’s population was counted as a U.S. territory (previously, the Kingdom of Hawaii took censuses).
• Immigrants were asked the year they arrived in the United States.
• People were asked how long they’d been married.
• American Indians — including those on tribal lands — were enumerated on the general questionnaires with the rest of the population. 

In the wake of the Gilded Age, the census changed again. President Theodore Roosevelt, who ran on trustbusting and rooting out corruption, hired census enumerators through the civil service system. Prior to this, Congress retained them as patronage positions.

The Census Bureau as it exists today was created in 1902, and moved from the Department of the Interior to the Department of Labor and Commerce. Prior to this, a “census office” was established and wound down each decade.

The 14th census revealed a major shift in population from rural to urban areas. Rural interests attempted to dampen the impact of this migration on their congressional representation.

Consequently, Congress delayed reapportionment of the House until 1929, using the results of the 1930 Census and skipping the 1920 Census returns entirely.

Due to international boundary changes after World War I, enumerators were instructed to report the province, state, region or city of respondents (or their parents) born in Austria-Hungary, Germany, Russia or Turkey. For any other foreign country, only its name was needed.

Between passage of the law funding the 1930 Census and the day counting began, the stock market crashed and The Great Depression began.

The Census Bureau was unequipped to process unemployment data as quickly as the public and institutions demanded. Rushed reports were published but seen as inaccurately low.

Congress called for a special unemployment census in January 1931, which confirmed the economic depression’s severity.

The 1930 Census was the last to ask all respondents detailed questions on topics like language, employment and veteran status.

The 16th census saw the first use of advanced statistical techniques like probability sampling, when answers from a random selection of individuals within a population are used to represent the whole.

These methods enabled the Census Bureau to ask additional demographic questions without surveying everyone in the country. It also eased data processing, allowing more time to create detailed tables and improve processing quality.

Census demographic, economic, manufacturing and mineral data were used to create the “Victory Plan” — the blueprint to win WWII.

• The U.S. Virgin Islands were enumerated.
• Respondents were asked if they had a Social Security Number.
• Women were asked if they’d been married more than once.
• Foreign-born respondents were asked about their citizenship status.
• Respondents answered detailed questions about work, income, and pension and retirement deductions.

With the nation’s expanded global presence after World War II, the 1950 Census sought to enumerate Americans abroad for the first time. Counting overseas service members was carried out in cooperation with the military, State Department and other federal agencies.

Family members reported other civilians abroad, but these data were excluded from official returns because they were of such poor quality.  

This is the most recent census to have all records made public, and the first to record the WWII “baby boom” (census records from each decennial census are made public 72 years after that census took place).

The eighteenth census of the United States was the first to rely primarily on self-enumeration. In urban areas, every household received a questionnaire by mail. An enumerator collected and reviewed the responses. 

This census asked detailed questions about housing condition, plumbing, heating, electricity, appliances and more.

This was the last census to show New York as the most populous state and the last to ask if homes had a radio.

To diminish complexity and processing burden, the Census Bureau reduced the number of inquiries on the long-form questionnaire from 66 to 23.

In most cases, enumerators only performed follow-up interviews with nonresponding households as part of the first true test of a “mail-out, mail-back” census.

In the wake of the Civil Rights Movement, respondents were asked to self-identify their race rather than having census enumerators decide.

It was also the last census to enumerate the Panama Canal Zone’s population.

The success of the 1970 mail questionnaire led to an expansion in 1980. About 95% of the U.S. population was counted this way.

Special attention was paid to improving enumeration methods for transient populations.

Suburban growth and the energy crises of the early 1970s fueled the Census Bureau’s expansion of its transportation questions.

• Respondents reported on the length of their commute.
• Unmarried and same-sex couples could list their significant other as a “partner.”
• All respondents were asked if they were of Spanish or Hispanic origin.

Computerized mapping systems debuted in data collection and tabulation processes. CD-ROMs of census returns were introduced (in addition to the traditional print, computer tape and microfiche).

For the first time, anyone with a personal computer could access some census data online.

A misprint mistakenly directed Spanish-speaking respondents to call an auto parts store in Kansas.

This was the last census to ask specifically about military service in World War I. It was also the last to enumerate Palau.

• Included a question asking what time people left for work.
• Los Angeles became the nation’s second-largest city (behind New York City), bumping Chicago to third.
• The Topologically Integrated Geographic Encoding and Referencing (TIGER) database — the first nationwide digital map of roads, boundaries and water — was created.

Some who received the short-form census questionnaire could respond via the internet for the first time. The worldwide web became the main distribution center for census data, as it is today. One could also buy the data on CD-ROM or DVD.

The short form had just seven questions, the shortest census questionnaire since 1820. The long form asked 52 questions of approximately 1 in 6 households (roughly a 17% sample).

Fewer reports were printed than in the past. The 2000 report series contained about one-tenth the number of pages of the previous decennial.

With three more questions than the prior census, the 2010 Census was still one of the shortest in history. It asked only 10 questions — respondent’s name, sex, age, race, Hispanic origin, ethnicity, relationship, how many people lived in the home, whether they occasionally lived elsewhere, and whether the home was owned or rented.

All respondents filled out what was traditionally referred to as the “short form.” The long form was retired and recast as the American Community Survey.

Due to cybersecurity concerns respondents could not submit answers over the internet, unlike the 2000 Census.

The 24th census was taken at the height of the COVID-19 pandemic. It was the first time that all households had the opportunity to respond to the census online.

Due to the pandemic, the Census Bureau needed extra time, causing it to miss the December 2020 apportionment count deadline.

As part of the 2020 communications campaign, the Census Bureau promoted a rendition of the song “This is Me” featuring a variety of Native Hawaiian and Pacific Islander artists from across the country.

• 10 states each had populations over 10 million.
• Responses were accepted online, by mail, by phone, through enumerators or administrative records.
• Enumerators were equipped with electronic devices allowing instant data upload.
• Satellite imagery was used to update the Census Bureau’s Master Address File.