The African-American population share is the key determinant of early voting behavior. In states where there are a lot of black voters, early voting is way, way up. In states with fewer African-Americans, the rates of early voting are relatively normal.
This works at the county level too. In Cuyahoga County, Ohio (Cleveland), which about 30 percent black, twice as many people have already voted early as in all of 2004. In Franklin County (Columbus), which is about 18 percent black and also has tons of students, early voting is already about 3x its 2004 total.
So when McCain’s pollster talks about Obama’s black vote being “locked in”, he is at best getting the story half-right. It’s true that there aren’t very many African-Americans who are reporting themselves as undecided. But any polling based on 2004 assumptions about what black turnout will look like is probably going to miss the mark significantly.
Most notably, early voting this year has already exceeded 2004 totals in three states: GA, NC, and LA. Based on Voting Rights Act compliance data, the African-American share of the early vote is 35% in GA (25% of total vote in 2004), 36% in LA (27% in 2004), and 28% in NC (26% in 2004).
It’s notable that the African-American share of early voting in these three states (especially the battleground state of NC) seems to be dropping steadily as Election Day approaches, which could validate (though I certainly hope not) my own theory that we’re beginning to see a southern white backlash to news reports of heavy African-American early voting. But with Obama adding somewhere between 5% and 10% to John Kerry’s 2004 margin among black voters, even a proportionate increase in African-American turnout will yield a significant net vote bonanza.