After spending some time searching, I found this (from 2010, but still a good find)
Interactive: Interracial Marriage: Who and Where | Pew Research Center It appears that the Midwest has the lowest rates of interracial in the country. Only 10.7% in the Midwest, compared to 12.6% in the Northeast. Even though the data is old, you can expect that the numbers have only increased in the Northeast (more Asian and Latino immigration, and high black in-migration from other states) than in the Midwest. I looked at the regions by demographics, the Midwest is currently 77% White, with the Northeast being 65% White, so it's not surprising. I also searched found that America's most racially segregated states and cities are in the Midwest, Milwaukee, Detroit, and Chicago being the top 3.