A press release on Households and Families: 2010 — from the Census Bureau — carried a headline on interracial/interethnic marriages. I think that’s probably important, and it would be a worthwhile read for that alone.
However, here’s other stuff of note:
People living alone: 25.8% of the 2000 population, 26.7% of the (larger) 2010 population.
Unmarried partner households: 6.8 million in 2010 (up from 4.9M in 2000) of opposite sexes (there are, you know, two). Same-sex unmarried households were 646,000 in 2010 — 0.6% of all households.
Total households = 117 million, of which 78M were “family” households (relatives living in same place) and 39M were “nonfamily” households (mostly the folks living alone).