From the U.S. Census Bureau: “In 2000, the racial/ethnic makeup of US residents was: White, 69 percent; Hispanic and Black, 13 percent each ; and Asian and other, six percent. By 2050, these per centages are projected to be: 50, 24,15, and 13.”
In 1977, The Census Bureau introduced the ethnic category of Hispanic.In the 2000 census four in ten of those who identified as Hispanic or Latino on the ethnicity question rejected all the racial categories or referred to “some other race.” This meant that 6% of the population placed themselves in ethnic or racial limbo.
2010 12% of young people called themselves multiracial. By 2050, 10% of whites and blacks and more than 50% of Latinos, Asians and native American Indians will be married to someone outside the racial group. This suggests that in 2020 25% of households will call itself multiracial.
See Nell Irvin Painter. The History of White People, pages 384-385 and Jennifer L. Hochschild. Racial Trends in the United States, Daedalus, Winter, 2005.