When final national race counts from the 2010 Census were released last month, they included more than nine million Americans who self-identified as belonging to two or more race groups. One of them was not President Barack Obama, child of a white mother and black father, who said last year that he described himself on his census form as “black.”

As columnist Gregory Rodriguez recently pointed out, the number of Americans who checked both “black” and “white” on their census forms grew by 134% from 2000 to 2010. (Among non-Hispanics, about 1.6 million reported being both black and white, but not any other race; among Hispanics, about 654,000 did so.) Rodriguez lamented the president’s decision not to include himself in more than one racial category.

The perception of Obama’s racial identity is quite different among black and white Americans. A Pew Research Center survey on race in late 2009 asked respondents “do you think of Obama as black or mixed race?” Among non-Hispanic whites, 53% said mixed race. But 55% of non-Hispanic blacks said he was black. Among Hispanics of all races, 61% said Obama is mixed race.