The share of Americans who identify themselves as multiracial has shrunk this decade, an unexpected trend in an increasingly diverse nation

Haya El Nasser:

About 1.9% of the people checked off more than one race in a 2005 Census Bureau survey of 3 million households, a meaningful decline from two surveys in 2000.

"There's no overall explanation" for the drop, says Reynolds Farley, a research scientist at the University of Michigan's Institute for Social Research who analyzed the trend.

The data show that the nation continues to wrestle with racial identity even in the face of growing diversity, he says. "We're a society where we still basically assume everyone is in one race," he says.

Multiracial groups fought that concept in the 1990s. The small but vocal movement gained momentum in 1997 after golfer Tiger Woods proclaimed his race "Cablinasian" — for Caucasian, black, American Indian and Asian. The spotlight hit other multiracial celebrities, including singer Mariah Carey, actress Halle Berry and Yankees shortstop Derek Jeter.

Mixed-race Americans lobbied the government to stop requiring people to choose one race category on Census and other federal forms. The 2000 Census for the first time allowed people to check more than one race. About 2.4%, or 6.8 million people, did so in the full Census.

The numbers were likely to rise as more children were born to mixed-race parents and multiracial organizations sprouted on college campuses. The opposite happened.

The Census Bureau's American Community Survey of 3 million households a year shows a clear trend, Farley says. In the 2000 ACS, 2.1% checked more than one race. The drop to 1.9% in 2005 is "a slight decrease but statistically significant," Farley says.

Jungmiwha Bullock, president of the Association of MultiEthnic Americans, is not surprised. Some believe that identifying more than one race negates racial identity, she says. "To say you're black and Asian doesn't mean you're not black," she says. "I don't say I'm half black and half Korean. I'm 100% black, and I'm 100% Korean."

The Census numbers "clearly underestimate how many people are mixed race," says Daniel Lichter, a professor at Cornell University who has studied intermarriages. "People aren't willing to define themselves as such."

Many multiracial people identify themselves as black if they grew up in a black neighborhood, he says.

"There's a lot of pressure from society to choose one race," says Sara Ferry, 28, a school psychologist in Philadelphia who has a black father and a Chinese-American mother. "That's unfortunate."

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