Though I have no way of proving it, I believe that you will find waaaay more ‘mixed marriages’ in The South then you ever will in the North.................
Census bureau stats as of 2010 say the majority of black-white intermarried couples are clustered from Baltimore to Richmond, but of course things may have changed in the past decade. Other hotspots are Chicago, Atlanta, Savannah, Norfolk—and basically the larger cities across the states. Intermarriage with Hispanics is a big thing in the western states. See page 10 for locations of black-white marriages:
https://www.census.gov/content/dam/Census/library/working-papers/2013/demo/2013-19.pdf