1. The census’ racial definitions have fluctuated wildly over time.
During the first few censuses, the government essentially lumped the country into two racial categories: white and black. But from 1850 to 1920 (with the exception of 1900), it enumerated mixed-race “mulattos” as well. “Quadroons,” defined as those with one-fourth black blood, and “octoroons,” defined as those with one-eighth black blood, were counted in 1890 and then never again. Meanwhile, those of Chinese, Japanese and American Indian descent started being counted at various points in the late 1800s and still are to this day.
For three decades “Hindu” was a category, whereas a category for Koreans was added in 1920, taken out in 1950 and then added back in 1970. A category for Mexicans likewise appeared on the 1930 census, only to be dropped immediately thereafter following complaints from the Mexican government. The most recent major change occurred in 2000, when it finally became possible to select more than one race.
In 2010, the census asked "Is Person 1 of Hispanic, Latino, or Spanish origin?" with checkboxes for no or yes, with several options for groups of countries. This question was posed in addition to the general race question.
READ MORE: Race in America
2. The census is enshrined in the U.S. Constitution.
Article 1, Section 2 of the U.S. Constitution calls for an “enumeration” to be made of the populace “within every subsequent term of 10 years.” In some ways, this idea was nothing new. The ancient Babylonians, Chinese, Egyptians and Romans all conducted censuses, as did William the Conqueror, who in 1086 inscribed info about England’s landowners into the so-called Domesday Book. Censuses are even mentioned in the Bible. However, the United States was one of the first modern countries to count all of its citizens and not just, say, military-age males. It was also the first country to constitutionally mandate a regular census and the first to use the census for apportioning political power. To this day, the number of seats each state holds in the House of Representatives depends entirely on census results.
3. Federal marshals used to carry it out.
Though best known for witness protection and hunting fugitives, U.S. marshals were also required by an act of Congress to count the inhabitants in their respective districts. As result, they hired roughly 650 assistants for the first census in 1790 and sent them door-to-door, more often than not in extremely rural terrain. Assistant marshals continued in this role for nearly a century. But in 1879, concerns over the census’ inefficiencies at last prompted Congress to replace them with specially trained enumerators. Congress then further professionalized the count in 1902 by creating a permanent government agency, the U.S. Census Bureau.
4. Some Founding Fathers doubted the census’ accuracy.
The first census turned up only 3.9 million (non-Indian) Americans, including nearly 700,000 slaves, a result that President George Washington, Secretary of State Thomas Jefferson and other high-ranking government officials dismissed as an undercount. “Our real numbers will exceed, greatly, the official returns of them,” wrote Washington, who put the blame on negligent census takers, as well as “the religious scruples of some…[and] the fears of others that it was intended as the foundation of a tax.” With so few people in the United States, he purportedly worried about looking weak in the eyes of the European powers.
5. Some census results have gone up in smoke.
Early census records from several states, including Delaware, Georgia, Kentucky, New Jersey, Tennessee and Virginia, have been lost to history. No one knows for sure what happened to them, but the prevailing theory holds that they were destroyed when British forces torched Washington, D.C., during the War of 1812. More than 99 percent of the 1890 census records are also gone, the result of a 1921 fire at the Commerce Department.
6. The census was an early user of both proto-computers and real computers.
Statistician Herman Hollerith began looking for a time-saving solution after census workers, tallying by hand, needed nearly a decade to process the results of the 1880 population count. By 1887 he had invented an electric tabulating machine that could read data from the holes on paper punch cards. It proved to be a great success, reducing census tabulation time by two-thirds, and was soon being sold to government agencies, utilities, manufacturers and railroads around the world. Hollerith’s business would later become part of IBM.
For decades, updated versions of his machine retained an important place at the Census Bureau. It was finally rendered obsolete in 1951, when the Census Bureau gained possession of UNIVAC I, the first non-military computer ever produced in the United States. A far cry from today’s laptops and smartphones, UNIVAC I was the size of a room and weighed about 16,000 pounds.
7. New York has always been the largest U.S. city.
The 1790 census documented 33,131 people in the Big Apple, which put it just ahead of Philadelphia as the most populous U.S. city. It has retained the top spot in all 22 censuses since, growing from a population of about 60,000 in 1800 to 515,000 in 1850 and then to 3.4 million in 1900 (two years after the five boroughs merged to form its present-day boundaries).
As of the last census in 2010, New York City had nearly 8.2 million people, more than Los Angeles, Chicago and Philadelphia (the second, third and fifth most populous cities) combined.
8. The largest state, on the other hand, occasionally changes.
Virginia started out as the most populous U.S. state—back when there were only 13 of them—with a 1790 population of around 700,000. New York then claimed the top spot in 1810 and remained there until being overtaken by California in 1970. As of 2010, the Golden State had 37.3 million residents, more than the 21 least populous states combined.
9. Only one state lost population during the last census period.
From 2000 to 2010, Michigan’s population fell 0.6 percent, from 9,938,444 to 9,883,640, a decline that experts largely attributed to job losses in the auto industry. Every other state in the country grew that decade, led by Texas, which gained 4.3 million people, and California, which gained 3.4 million.
10. The census is not cheap for taxpayers.
Though the inaugural census cost just $44,000 to conduct, the price tag has since ballooned to an estimated $6.5 billion in 2000 and $12.9 billion in 2010. Inflation and population growth aside, much of the expense comes courtesy of residents who don’t fill out their census questionnaires.
“It costs us just 42 cents in a postage paid envelope when households mail back their … forms [and] about $25 per person if we have to go out and knock on the doors,” Robert M. Groves, the Census Bureau’s then-director, said in a 2010 statement. To help keep expenditures stable for the 2020 count, the bureau allowed residents to respond via the Internet.