Age/Education, not race.
In the wake of the narrow passage of the anti-gay-marriage Proposition 8 in California, there was a lot of unhappy talk about African-American Obama voters making the difference. But a recent survey by the Public Policy Institute of California looks at the results from various optics, and concludes that educational and income levels, and age, were the most important variables in determining the vote.
Indeed, there's an extraordinarily strong correlation on these factors. Those with a high school education or less favored Prop 8 by a 69-31 margin; those with a college degree opposed it 57-43; and those with some college but no degree supported it 57-43. It's the same story on income: those earning under $40,000 supported Prop 8 by a 63-37 margin; those earning over $80,000 opposed it 55-45; and those in the middle supported it by the same 52-48 margin as the electorate as a whole. Least surprisingly, voters under the age of 35 opposed Prop 8 by a 57-43 margin; those 55 and older backed it 56-44; and those in-between split evenly.