WASHINGTON — Hispanics accounted for more than half of the U.S. population increase over the last decade, exceeding estimates in most states as they crossed a new census milestone: 50 million, or 1 in 6 Americans.
Meanwhile, more than 9 million Americans checked two or more race categories on their 2010 census forms, up 32 percent from 2000, a sign of burgeoning multiracial growth in an increasingly minority nation.
The Census Bureau on Thursday released its first set of national-level findings from the 2010 count on race and migration, detailing a decade in which rapid minority growth, aging whites and the housing boom and bust were the predominant story lines.
Analysts said the results confirmed a demographic transformation under way that is upending traditional notions of racial minorities, political swing districts, even city and suburb.
"These are big demographic changes," said Mark Mather, an associate vice president at the nonprofit Population Reference Bureau. "There is going to be some culture shock, especially in communities that haven't had high numbers of immigrants or minorities in the past."
"By 2050, we may have an entirely new system of defining ourselves," he said.
According to data released Thursday, Americans continued their decades-long migration to fast-growing parts of the Sun Belt. Their move to big states such as California and Texas as well as fast-growing Mountain West states pushed the nation's mean center of population roughly 30 miles southwest to a spot near the village of Plato, Mo.
African-Americans in search of wider spaces increasingly left big cities such as Detroit, Chicago and New York for the suburbs, typically in the South. Both Michigan and Illinois had their first declines in the black population since statehood as many of their residents opted for warmer climes in the suburbs of places such as Atlanta, Dallas and Houston.
The smaller numbers were a surprise to some city officials, including New York Mayor Michael Bloomberg, who questioned the census count of 8.2 million for his city and suggested immigrants may have been missed.
Census director Robert Groves said the agency had not yet received any formal complaints about the census count and that overall indicators showed high accuracy in 2010 compared to 2000.
After initial fears of low participation, the 2010 count of the Hispanic population came in 900,000 higher than expected, matching or surpassing census estimates in 37 states, according to the Pew Hispanic Center, a nonpartisan think tank.
Many of the biggest jumps were in the South, including Alabama, Louisiana, North Carolina and Louisiana, where a small but fast-growing Hispanic population was fueled by an influx of immigrants during the housing boom.
Multiracial Americans now make up 2.9 percent of the U.S. population, a steadily growing group — even if it did not include President Barack Obama, who identified himself only as African-American on his census form. Obama's mother Ann Dunham, a white woman from Kansas, married his father, the Kenyan native Barack Obama Sr.
The vast majority of multiracial Americans lived in California, Texas, New York and Hawaii. The most numerous race combinations were white-American Indian or Alaskan Native, white-black and white-"some other race." In some cases, white Hispanics may be opting to list themselves as multiracial in the "some other race" category, which would put the actual number of multiracial Americans lower than the official tally of 9 million.