Poking around the CensusScope site I found some interesting maps to compare & contrast. Here are the frequency of "nuclear families":
No big surprises here. Utah & the Heartland have a high proportion of households composed of nuclear families. The Black Belt, not as much. How about families composed of people "living in sin"? That is, unmarried couples.
Looks like "Greater New England" likes the sin. Though that isn't a function of climate, as Florida mirrors New England with high rates of cohabitation and low rates of nuclear families. Now how about families where grandparents are responsible for grandchildren?
This patterns seems prevalent among ethnic minorities.
