When the 2010 census asked people to classify themselves by race, more than 21.7 million - at least 1 in 14 - went beyond the standard labels and wrote in such terms as "Arab," "Haitian," "Mexican" and "multiracial."
The unpublished data, the broadest tally to date of such write-in responses, are a sign of a diversifying America that's wrestling with changing notions of race.
The figures show most of the write-in respondents are multiracial Americans or Hispanics, many of whom don't believe they fit within the four government-defined categories of race: white, black, Asian/Pacific Islander or American Indian/Alaska Native. Because Hispanic is defined as an ethnicity and not a race, some 18 million Latinos used the "some other race" category to establish a Hispanic racial identity.
"I have my Mexican experience, my white experience but I also have a third identity if you will that transcends the two, a mixed experience," said Thomas Lopez, 39, a write-in respondent from Los Angeles. "For some multiracial Americans, it is not simply being two things, but an understanding and appreciation of what it means to be mixed."
Lopez, 39, the son of a Mexican-American father and a German-Polish mother, has been checking multiple race boxes since the Census Bureau first offered the option in 2000. Marking off the categories of Hispanic-Mexican ethnicity, "other" Hispanic ethnicity and a non-Hispanic white race, Lopez opted in 2010 to go even further. He checked "some other race" and scribbled in a response: "multiracial."
More than three million write-ins came from white and black Americans who appear to have found the standard race categories insufficient. They include Arabs, Iranians and Middle Easterners, who don't fully view themselves as "white" and have lobbied in the past to be a separate race category. They are also Italians, Germans, Haitians and Jamaicans who consider ancestry a core part of who they are.
Roughly half a million black Americans - between 1 and 2 percent of their total population - wrote in answers to signify their preferred term for black. Among them: African-American, Afro-American, African, Negro, mulatto, brown and coffee. More than 36,000 described themselves as "Negro" in whole or in part. The term, which was listed as an example on the 2010 census form, drew criticism from some black groups for being outdated and insensitive.
Lopez, a mechanical engineer who helps run a multiracial awareness group, said he believes the government should provide a wider range of choices on survey forms. "Right now there's a significant segment of the population who feel that the boxes do not adequately represent them," he said.
While the issue of racial identity can be deeply individual, it is also highly political: census data are used to enforce anti-discrimination laws, to distribute more than $400 billion in federal aid for roads, schools and health care, and to draw political districts based in part on a community's racial makeup. Over the past decade, the number of people identifying as "some other race" jumped by 3.7 million, or 24 percent. Experts say an increase in the write-in responses could signify limitations to the form and potentially skew government counts.