The most common type of interracial union, making up 41 percent of the total, is Hispanic/white (black/white marriages are only 11 percent of all interracial marriages). 30.8 percent of Asians who married in 2008 married someone of another ethnicity -- but it was heavily skewed toward women. While 39.5 percent of Asian women married non-Asian men, only 19.5 percent of Asian men married non-Asian women.
There are also some geographical differences (there's an interactive graphic here). While 21.4 percent of marriages in 2008 in the West were interracial, only 10.8 percent of those in the Midwest were. The highest proportion -- 28 percent -- was in Nevada. The lowest? Mississippi, at 5 percent.
Yglesias chimes in:
I think the upshot of this is that the country will be “whiter” in 2050 than naive demographic projections suggest and that will largely be because a very substantial portion of the descendants of today’s Hispanics and Asians will be considered white.