The data comes from the U.S. Election Project. It's imperfect as a predictor, for reasons nicely outlined by the project's Michael McDonald, and which we summarized last week. Registration doesn't equal expected turnout, and variations in how turnout works in each state mean that we're comparing early voter apples with mail-in voter oranges. Nor do early vote counts necessarily mirror final election results.
That said, here's how the data looks. As of the the Election Project's latest update, 11.6 million Americans have voted. Where the numbers are broken down by party (or, in the case of Georgia, race) we plotted them against registration. The smaller dots on the line show past data updates. Some states were added later than others, or weren't updated as regularly.
There has been a lot of of per-state analysis over the past few weeks, including McDonald's own assessments and a good overview from our Reid Wilson. The trends, though, are clear from the graph above: dips in the percentage of early votes from Republicans in several states and increases in the vote from Democrats and those who don't identify a party.
By picking out states individually, it's easier to see. Take Georgia.
Over the past few updates, there's been a clear trend in Georgia: the percentage of the early vote that's coming from white voters has declined, while the percentage from black voters has increased. Each is now at about the level of registration in the state, which is probably good news for Democrats looking to pick off both a Senate seat and a governor's seat. A key factor identified by the New York Times on Wednesday: Sunday post-church voter mobilizations, which inspired a surge in black votes.
McDonald points out that this was predictable. As in-person voting (which usually kicks in closer to Election Day) begins and spreads, it tends to favor boosts in Democratic turnout.
Here's a look at some other states.
Colorado, which also has both a tight governor's and Senate race, has seen a steady increase in the biggest group of voters: those who aren't Democrats or Republicans. Meanwhile, the percentage of the early vote coming from Republicans has fallen -- but it's still outpacing the Democrats. The further above the line the dots appear here, the better.
(Colorado is also using an all-mail ballot system for the first time, which makes the state particularly interesting to watch.)
In Florida, home to a very tight governor's race, Democrats are under-performing their registration. That's bad news because, as Wilson wrote on Tuesday, Republicans feel confident that they'll have better relative turnout on Election Day. Even though Democrats outnumber Republicans in the state, they're trailing in the early vote.
North Carolina offers good news for Democrats. They lead in the early vote and have more of the voter registration. Plus, the race between Sen. Kay Hagan (D) and Thom Tillis (R) has been tightening. If by Election Day Tillis has a steady lead in the polls, it will be worth remembering that a lot of the vote -- nearly 600,000 so far -- was already in the bank, and almost certainly favoring Hagan.
This is why campaigns love early voting, of course. It gives them the chance to spread get-out-the-vote efforts over a month, and to have some sense of where they stand. It is not longer the case that the only votes that count are those on Election Day.