Nine million people reported more than one race in the 2010 Census and made up about 3 percent of the total population. Ninety-two percent of people who reported multiple races provided exactly two races in 2010; white and black was the largest multiple-race combination. An additional 8 percent of the two or more races population reported three races and less than 1 percent reported four or more races.
Three quarters of multiple race combinations were comprised of four groups in 2010: white and black (1.8 million), white and “some other race” (1.7 million), white and Asian (1.6 million), and white and American Indian or Alaska Native (1.4 million).
Source: U.S. Census