http://en.wikipedia.org/wiki/Interracial_marriage_in_the_Uni...
Note that the "Approve" line doesn't cross the "Disapprove" line until the mid-1980s, long after the USSC had spoken. With same-sex marriage on the other hand, the "Approve"/"Disapprove" cross-over happened a bit over three years ago and the USSC has yet to speak as definitively as it did in Loving v. Virginia.
(One could argue that in invalidating most of DOMA, the USSC has already spoken strongly - if not definitively - in favor of same-sex marriage, and therefore that we should use that decision when making analogies to Loving. I'm not sure about that.)