Early voting numbers don't tell us who's going to win
According to data from the University of Florida, more than 80 million people voted early in the 2024 election. That's likely to be about half of the final number of voters.
Pre-Election Day voting has steadily grown in popularity over the last couple decades. Even before the pandemic, around 40% of voters in the 2016 election cast their ballot before Election Day. In 2020, of course, the number of people voting by mail surged, and almost 70% of people voted before Election Day — but this number returned to a more normal 50% in 2022.
What can we learn from these early votes? Not much. Even though early votes, like all ballots, aren't reported until polls are closed, some people try to read into the early voting numbers by looking at the party registration of the people who have turned out so far. But there are a few problems with that: First, people don't necessarily vote for the same party they're registered with. Second, we have no insights into who independents are voting for.
Third, and most importantly, early voters are an incomplete picture of the electorate. Even if early voters are disproportionately Democratic or Republican, we don't know if that's because Democrats or Republicans are unusually fired up to vote or just because they're shifting their voting patterns and deciding to vote early instead of on Election Day. Basically, any lead that one party amasses over the early-voting period can be totally wiped out with a strong Election Day turnout from the other.