In March 2018, the Commerce Department announced that it would include a question on citizenship in the 2020 census—the first such question to be asked of all U.S. households , and one that say they would sue over.

The census, a Constitutionally-mandated survey of the U.S. population since 1790, has a long history of being used as a political tool. Critics of the latest move the new citizenship question will be used to identify and deport Latino immigrants or reapportion funding and representation in areas where they live. In the past, census information has been used to reinforce “pure” white ancestry as the standard for full citizenship.

Many of the changes the census has gone through have to do with race and power in America. This is particularly evident when looking at the censuses taken between 1850 and 1930, a period of rapid change that saw the end of slavery and the beginning of Jim Crow. During this time, the census sought to classify how much African ancestry a person had, thereby reinforcing a social structure that denied full citizenship to people with any amount of African heritage.

Early South Carolina census that required one to fill out the following columns reflecting their household, "Free white males of 16 years and upward including heads of families, Free white males under 16 years, Free white females including heads of families, All other free persons, and Slaves." (Credit: Fotosearch/Getty Images)
Fotosearch/Getty Images
Early South Carolina census that required one to fill out the following columns reflecting their household, “Free white males of 16 years and upward including heads of families, Free white males under 16 years, Free white females including heads of families, All other free persons, and Slaves.”

The very first census sorted the population into three racialized citizenship categories: “Free white males [and] females”; “All other free persons”; and “Slaves.” In 1820, “All other free persons” was later altered to “Free colored males and females.” However, the biggest change was the division between “black” and “mulatto” a few decades later.

“The ‘mulatto’ category was added in 1850 at the request of a ‘racial scientist,’ Josiah Nott,” says , a political science professor at MIT and author of . Nott was a white slave owner in Alabama who “thought that blacks and whites may have been different species,” she says. He persuaded Joseph Underwood, a senator from Kentucky, to include “mulatto,” on the census so that he could study mixed-race people with some African ancestry and see, for example, “if there was any kind of drop-off in their lifespan.”

In 1890, two new categories appeared: “quadroon” and “octoroon,” which indicated one-fourth and one-eighth African ancestry, respectively. Though these classifications only stuck around for one census cycle, they signify that white lawmakers, scientists, and statisticians “were getting more interested in this notion of purity, and purity of whites and not of blacks,” says Nobles.

The official US Census form from 2010, providing many more specific options for identifying race than in past forms. (Credit: Paul J. Richards/AFP/Getty Images)
Paul J. Richards/AFP/Getty Images
The official US Census form from 2010, providing many more specific options for identifying race than in past forms.

According to the white supremacist concept of the “one-drop rule,” a person with any African ancestry could not access the same social, legal, and economic privileges reserved for white people. However, throughout the 21st century, this logic frequently broke down when put before the legal system, since race is a social construction rather than a biological reality.

By 1930, white statisticians acknowledged that deciding whether someone is “black,” “mulatto,” “quadroon” or “octoroon” on a census form is subjective, and replaced all of these categories with “Negro” (that census also included “Other,” “Indian,” “Mexican,” and five categories for people from South or East Asia). Since then, the census has added many other racial categories and updated its language, but it continues to be a .

That’s because the census isn’t just a tally of how many people are in the United States. It decides which demographics need what resources, so choosing the correct questions and language is extremely important.