Voters line up to cast their ballots at the Stamford Government Center on the first day of early voting on October 21 in Stamford, Connecticut.

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CNN  — 

Two weeks to Election Day and millions of Americans are voting every day, either early in person or by returning mail-in ballots.

Early Tuesday, news reports were citing that more than 15 million Americans had voted. Checking the early voting data CNN gets from election officials and the firms Catalist and Edison Research around noon Tuesday, the figure had grown to more than 18 million. It will continue to grow. For reference, more than 150 million total ballots were cast in 2020.

This year, in the key state of Georgia, Secretary of State Brad Raffensperger said Sunday on CBS News that he expects up to 70% of the votes in his state will be cast before Election Day.

One interesting development in the data from Catalist is that in these early reports, there are some hints that Republicans may be cutting into the Democratic edge in early voting. More Republicans than Democrats have cast ballots in Nevada, and the parties are on par in North Carolina, according to the early data. That might cause concern for Democrats who remember 2020, when Democratic mail-in votes were critical to Joe Biden’s victory. It could also simply mean Republicans are doing more to encourage early voting.

In any event, more early Republican votes could cut down on what was perceived as a “blue shift” when Democratic-leaning, mail-in ballots were counted after Republican-leaning Election Day ballots in key states in 2020.

Don’t draw conclusions from the early vote

For starters, all of the votes – those cast early and those cast on Election Day – count equally. This is also a much different year from 2020. In that pandemic year, far more Americans voted by mail than are expected to this year. Much of the early vote this year will be cast in person.

Plus, while former President Donald Trump has not exactly embraced early voting, Republicans strategists who support him have. They have encouraged his supporters to cast votes early.

Look at North Carolina

Trump won the state in both 2016 and 2020, but he is on defense there this year, holding multiple campaign events across the state this week.

Nearly equal percentages of Republicans, Democrats and independents have cast ballots in North Carolina so far, either by mail or early in person.

The Republican strategist Doug Heye said Tuesday on CNN that he’s not looking at the percentages of Republicans or Democrats casting ballots early in the state.

“I’m looking at the unaffiliated voters in North Carolina and what are they going to do,” he said. “That’s what’s going to be what decides this election.”

Nearly 1.4 million ballots have already been cast in North Carolina, according to CNN’s data. Compare that with nearly 5.5 million total votes cast in 2020.

Heye also argued that in states like North Carolina, where the outcome could be determined by very small margins, it’s the few undecided voters who could ultimately decide the outcome.

“If you voted early, obviously you’ve already made up your mind,” Heye told CNN’s John Berman. He pointed to events held this week by Vice President Kamala Harris alongside the disaffected Republican former Rep. Liz Cheney that could appeal to those remaining waffling voters.

In other words, it’s far from over.

Look at Georgia

In Georgia, more than 1.7 million people have cast ballots, a large and growing chunk of voters in a state where a little fewer than 5 million ballots were cast in the 2020 presidential election. But while Georgia voters do not register by party, there are other data points to consider.

More women, making up 55% of the early vote so far, have voted in Georgia, compared with men, who have made up 45%, according to the ballots for which Catalist has data. Biden won more than half of Georgia women in 2020, and women also accounted for more than half of voters that year, according to CNN exit polls.

Data reported as of noon ET on October 22.

On the other hand, the largest age group that has cast early ballots in Georgia is older voters. Trump won them in 2020, according to exit polls.

Data reported as of noon ET on October 22.

Black voters were about 29% of Georgia voters in 2020, according to exit polls, and they account for 31% of voters so far in the state’s early vote in 2024.

Data reported as of noon ET on October 22.

Look at other key states

In Nevada, where fewer than 1.5 million voters cast ballots for president in 2020, a little fewer than 250,000 have cast votes so far in 2024. But unlike in Georgia, more men than women have cast ballots, according to the available data.

It’s the opposite in Wisconsin and Pennsylvania, the Rust Belt states where more women have cast early ballots. Fewer than 400,000 ballots have been cast so far in Wisconsin, compared with more than 3 million ballots cast for president in 2020. Close to a million ballots have been cast early in Pennsylvania in 2024, compared with nearly 7 million total votes in 2020.

In Georgia and Pennsylvania, White voters account for a slightly larger share of ballots cast so far compared with this point in 2020, while Black voters account for a slightly smaller share. The share of Latino and Asian voters has stayed consistent compared with four years ago. In Wisconsin, where 89% of voters so far are White, the racial breakdown is about the same as it was at this point in 2020.

Hard to compare 2020 with 2024

Beyond the differences in how people might vote this year, it’s hard to compare 2020 with 2024 because the populations in key states and across the country have changed in the past four years, according to CNN senior political analyst Ronald Brownstein.

Brownstein talked to the Brookings Institution demographer William Frey, who argues in a new analysis that the portion of college-educated White voters and voters of color who tend to support Democrats has risen by about a percentage point nationwide. The portion of working-class White voters who increasingly form that backbone of the modern Republican Party has dropped more quickly in Wisconsin and Michigan than it has in Pennsylvania.

These small-seeming changes could have a very big effect, Brownstein said.

“It kind of looks like a butterfly-effect race where … any flutter in the environment might be enough to change the dynamic between these two coalitions that are utterly antithetical in what they want for the country and almost exactly equal in size,” Brownstein said on CNN.

CNN’s Molly English, Matt Holt and Ethan Cohen contributed to this report.