According to 2020 Census data, the number of individuals identifying with more than one race increased from 9 million in 2010 to 33.8 million today, an astonishing 276 percent. But has the group really expanded that dramatically — or have the census’s definitions changed over time? And what does that count mean for how Americans understand public policies that hinge on racial identification?

The census’s racial categories have shifted dramatically over the past two centuries

Many observers, including scholars Margo Anderson and Stephen E. Fienberg, have noted that in the United States, counting people has never been race-neutral. The U.S. census was created in 1790 to determine taxation; following the constitution, it counted enslaved Black people as three-fifths of a person.

Since then, the census’s racial categories have shifted as the United States’ demographics and politics have changed. Historically, the U.S. government subscribed to the false idea that race can be measured by fractions of a person’s ancestry; Black Americans, in particular, were legally subjected to this fiction. Until 1960, a census enumerator determined Americans’ race according to instructions for different racial categories on each census; from 1960 onward, most people identified their race in census forms mailed to them.

Political scientist Melissa Nobles’s research has found that scientists’ desire to measure the alleged negative effects of race-mixing, particularly between Black and White people, prompted the census to create categories for counting Black people. Categories based on percentage of Black ancestry have changed over time, beginning with “Black” and “mulatto” in 1850, with the second word used to mean someone with both Black and White ancestry. In 1890, the census added “quadroon” and “octoroon” for someone who had one Black and three White grandparents or one Black and seven White great-grandparents; “mulatto” was someone who had “three-eighths to five-eighths black blood.” In 1900, the census consolidated all those categories back into “Black” and then restored “Black” and “mulatto” in 1910 and 1920.

After 1920, the census eliminated categories denoting percentages, influenced by polygenists who believed different races did not evolve from a common ancestor and endorsed “racial purity” and white supremacy. Subcategories were replaced by the “one-drop rule,” a legal and social practice that defined anyone with a Black ancestry as Black — excluding Black people from Whiteness’s legal and social protection.

The census added the “mark one or more races” instruction in 2000, to great controversy

Political scientist Kim Williams’s research reveals that multiracial organizations and some multiracial adults pressured the census to add “multiracial” as an option. As Williams explains, “affluent, well-educated, suburban, white women who were married to black men were leading most of the grassroots groups, on behalf of their children.” They succeeded, and in 2000, Americans were able to identify themselves as belonging to more than one racial category, and to be counted as identifying with “two or more races.”

That had political implications. Civil rights organizations such as the NAACP and the Asian American Legal Defense and Education Fund opposed the change for fear that people identifying as multiracial would reduce the power of minorities and mask inequities among racial groups. Legal scholar Alynia Phillips argues that Republicans supported multiracial categories, hoping that this would reduce the social importance of racial categories and encourage a more “color-blind” society.

Multiracial” differs fairly dramatically from “octoroon” and the like, in no small part because it emerged from the decriminalization of interracial marriages in the 1967 U.S. Supreme Court case Loving v. Virginia. But some scholars argue that this, too, is a problematic category, falsely implying that races start as biologically distinct and are mixed through biology.

What will expanding populations of multiracial Americans mean for U.S. politics?

While every multiracial category grew at precisely the same rate, the growth in multiracials accounted for most of the overall change in each racial category. The number of people identifying as Black and White, for example, nearly doubled from 1.8 million in 2010 to 3.1 million in 2020. Overall, the percentage of the White population decreased by 8.6 percent, while White plus another race increased 316 percent over 2010. Asian Americans — the fastest-growing racial group in America — grew 35.5 percent, while Asian plus another race grew 55.5 percent.

Many researchers have been investigating what multiracial identification means for society and politics. For instance, sociologist Hephzibah Strmic-Pawl found that some Asian-White biracial people felt they weren’t discriminated against in American society, while some Black-White participants encountered racist, anti-Black attitudes.

Meanwhile, social scientists Natalie Masuoka and Lauren Davenport find that people who identify as multiracial are more likely to be Democrats, support affirmative action and oppose the death penalty than are people who identify only as White.

Multiracials and the future of U.S. politics

As the number of multiracial Americans grows, what will it mean for policies focused on racial inequality: employment discrimination, affirmative action, housing discrimination, reparations to Black Americans, and representation in political office? Given how anti-Black racism affects multiracials with Black ancestry, looking closely at Black multiracials will be important in civil rights law.

Many of those who identified as multiracial are young. Will they wish to see multiracial leaders in office? One such political figure is Vice President Harris, well-known to be Black and Indian American. One of us, Danielle Casarez Lemi, has done research suggesting that multiracial lawmakers advocate for non-White communities through legislative racial caucuses dedicated to a specific racial group’s concerns, such as the Congressional Asian Pacific American Caucus. But multiracial-Black lawmakers may be treated differently from one another, depending on which parts of their ancestry are most physically apparent, much as judges once determined race by looks. And some voters may prefer candidates identified as Black and White, depending on the circumstances.

This year’s census confirms yet again that racial identities in the United States are complex and nuanced, as they always have been.

Danielle Casarez Lemi (@D_Lemi) is a Tower Center fellow at the John G. Tower Center for Public Policy and International Affairs at Southern Methodist University.

Sara Sadhwani (@sarasadhwani) is an assistant professor of politics at Pomona College and a senior researcher at AAPI Data.