Just to echo Rob’s point, I suspect much of the split-ticket voting is driven by the different standards by which some voters evaluate their member of Congress versus the President. Constituency service at the local level can trump partisanship for at least some voters. So, to be clear, I’m not saying all ticket splitters are deliberately voting for divided government, although I suspect some are. If I can dig up individual data beyond polls, I’ll pass it on.

- Matt

Note that that African-American presidential vote skews consistently toward the Democratic presidential candidate in recent elections. So, 88% of African-Americans voted for John Kerry in 2004, and 90% supported Gore in 2000. Moreover, the proportion of the vote this year by African Americans was about the same as it was in 2008. All a long way of saying that I doubt voter suppression was the primary factor driving their vote, although it certainly may have motivated some African-Americans. But they have been a strong and consistent vote for Democrats for a long time now.

If you are interested in polling data, you can start with the national exit polls (CNN Election Center has them) and you can look at any of the pre-election polls that tapped into voters’ attitudes, such as those issued by Pew.