The 2010 Census showed that people who reported multiple races grew by a larger percentage than those reporting a single race. According to the 2010 Census brief The Two or More Races Population: 2010, the population reporting multiple races (9.0 million) grew by 32.0 percent from 2000 to 2010, compared with those who reported a single race, which grew by 9.2 percent.
Overall, the total U.S. population increased by 9.7 percent since 2000, however, many multiple-race groups increased by 50 percent or more.
The first time in U.S. history that people were presented with the option to self-identify with more than one race came on the 2000 Census questionnaire. Therefore, the examination of data from the 2000 and 2010 censuses provides the first comparisons on multiple-race combinations in the United States. An effective way to compare the multiple-race data is to examine changes in specific combinations, such as white and black, white and Asian, or black and Asian.For census purposes, race is a matter of self-identification. The change here stems less from any shift in ancestry patterns than from an increased tendency to report multiple races. In turn, this tendency may stem from evolving attitudes toward race, greater awareness of multiracial backgrounds (perhaps reflecting the historic election of a multiracial president), and in some cases, genealogical discoveries.