In a closely divided election — like the one last week between President Obama and Governor Romney — small blocs of voters can take on outsized importance, especially when they lean strongly to one side.

In keeping with history, the Democrats did exceedingly well with black voters — better than 90 percent. But that’s only slightly better than Democratic candidates in recent history.

Obama also got over 70 percent of Hispanics, a small but growing portion of the electorate. He did even better — about 3 to 1 — among the small but rapidly growing Asian American population (David Brooks has an interesting column about that).

Obama also dramatically outperformed Romney among the 5 percent of exit poll respondents who identified themselves as gay. From the NYT’s Gay Vote Seen as Crucial in Obama’s Victory (written by Micah Cohen, btw, a regular contributor to FiveThirtyEight):

But the backing Mr. Obama received from gay voters also has a claim on having been decisive. Mitt Romney and Mr. Obama won roughly an equal number of votes among straight voters nationwide, exit polls showed. And, a new study argues, Mr. Romney appears to have won a narrow victory among straight voters in the swing states of Ohio and Florida.

Mr. Obama’s more than three-to-one edge in exit polls among the 5 percent of voters who identified as gay, lesbian or bisexual was more than enough to give him the ultimate advantage, according to the study, by Gary J. Gates of the Williams Institute at the U.C.L.A. School of Law, in conjunction with Gallup. The results are consistent with earlier research on the size and political beliefs of gay voters.

Gay voters are another demographic group — along with African-Americans, Latinos, Asian-Americans and Jews — in which Democrats have been winning big victories over Republicans. Some of the groups are small, but together they make up about one-third of the electorate, forcing Republicans to win large victories among the remaining two-thirds of voters to win elections.

There’s also a growing number of men and women telling exit pollsters that they are gay — 6.4 percent of those from 18 to 29 compared to just 1.9 percent of those over 65.

Obama’s statements in support of same sex marriage have certainly helped his standing with gay voters, who also tend to take other socially liberal positions. But there are plenty of gay voters who hold libertarian or fiscally conservative views who could conceivably be convinced to vote Republican, no matter a politician’s stand on a single issue like gay marriage. Also, it’s worth noting that gays are also members of other groups — white, black, Asian, etc.

Almost certainly, some of the Republican establishment will try to tailor future policy positions to appeal to specific blocs of voters. It will be interesting to see if that works, or if Republican social policies will need to be overhauled dramatically to appeal to these various minority groups.

And if the party’s positions on social issues become more libertarian, what will happen to the base of social conservatives?

Lots of interesting trends to watch.