Great article in the most recent Economist — i highly recommend reading it:

The great American political divide, as seen through the congressional districts of Nancy Pelosi and Dennis Hastert

Some good quotes:
“Only 35% of San Franciscans own their own houses, compared with a national average of 70%.”

“But San Francisco now has one of the lowest proportions of families with children in the country (it has more dogs than children, say some). Almost 70% of the population is single.”