With five days to go, registered Republicans also lead Democrats in early voting in Arizona, while Democrats are also ahead in Colorado and Iowa.
More than 30 million votes have been cast already across 38 states with early voting. And with five days to go, both Hillary Clinton and Donald Trump are encouraging their supporters to hit the polls early. So far, about 7.4 million registered Democrats and about 6.4 million Republicans have done just that.
CNN has partnered with Catalist, a data company that works with progressive candidates and groups, to receive detailed early vote return information this year. Catalist's voter list connects returned ballots with demographic and registration information, such as party registration, gender and age, and allows a closer look at who has already cast a vote.
These are not results -- ballots aren't counted until Election Day. But the findings provide clues on who is voting and which party is turning out to vote. And in states that track party affiliation, it's important to remember that not all Democrats are voting for Clinton, and not all Republicans support Trump.
Here's a look at the early voting data from several battleground states:
There's good news for both parties in Arizona, where about 1.3 million people have already voted.
Registered Republicans are ahead right now -- they lead by about 71,000 votes or 5.5%. But at this point four years ago, the GOP had a 10% advantage over Democrats. Perhaps sensing an opening, the Clinton campaign decided this week to pump an additional $1 million into Arizona for TV ads.
But the good news for Republicans here is that it appears they're gaining ground. One week ago, their lead over Democrats was only about 11,500. Today that lead is more than 71,000.
In Arizona, about 2 in 3 votes were cast early in 2012.
Colorado is a state where the election is almost entirely conducted by mail. And with voting underway, there is good news for Democrats: They've consistently led Republicans in terms of ballots returned.
Today, they're ahead by more than 18,500 votes, or about 1.5%. Four years ago at this point, Republicans had a lead of more than 33,000 votes, or about 3%. That is a significant flip.
But there are some new polls out of Colorado that show a tightening race, and there are some indications in the early voting numbers to back that up. The Democratic lead one week ago was about 5.6%. That narrowed to about 2.4% on Tuesday and stands at 1.5% today.
Republicans have been steadily ahead in the early vote by about 0.5% over the past week. Maybe that's why President Barack Obama rallied voters Thursday in Miami and Jacksonville, hoping to turn things around.
The GOP lead is tiny -- it's only about 16,000 votes out of more than 2.7 million cast -- but it's a strong sign for Republicans because at this point in 2008, they trailed Democrats by more than 73,000 votes.
Turnout increased across the board, but it rose at difference paces for different racial groups. Latinos had the largest spike in terms of raw votes, boosting their turnout by 129% from 2008. White voters increased their turnout by 55%. And even though African-American turnout is up by 24%, that is clearly a slower growth rate than the other racial groups, and their share of the electorate dropped from 2008.
What does this mean? For Democrats to win, they're likely hoping the big gains among Latino voters are enough to overcome whatever drop-off there is in the African-American vote.
Democrats lead Republicans in Iowa, but they've been consistently behind their winning 2012 pace.
Right now, about 41,000 more Democrats than Republicans have voted in the Hawkeye State. But at this point four years ago, they had an edge of more than 60,000 votes. According to the data, their advantage is shrinking as Election Day draws closer, but this also happened in 2012, when Obama won.
All that being said, a majority of voters in Iowa typically cast their ballots on Election Day.
The early vote in Nevada has tracked closely with 2012, a year when Democrats built a significant lead during the early voting window. Obama relied on that lead to help him carry the state on Election Day.
Registered Democrats are ahead by about 29,000 votes right now over registered Republicans. That's a slight drop from the 31,000-vote lead they had on Tuesday. But their lead is larger today than it was one week ago. Four years ago at this time, Democrats were ahead by about 38,000 votes, or 7.6%.
The early vote is crucial in Nevada: Almost 70% of votes came early in 2012.
Democrats are padding their lead in North Carolina, consistently increasing their raw vote advantage over Republicans as more early voting locations open across the Tar Heel State.
Right now, registered Democrats are ahead by about 243,000 votes statewide. That's an impressive showing, but at this point in 2012, the Democratic lead was more than 307,000 votes. In other words, Democrats are lagging a bit behind their pace from 2012, a year when they narrowly lost the state.
The reason might be in the demographics. African-American turnout is lower this year and they have dropped as a share of the early electorate from 28% in 2012 to about 23% today. As more polling places open this week -- especially in counties with a large black electorate -- their turnout might tick up.
The overwhelming majority of African-Americans that voted already in North Carolina were also registered Democrats, so when their vote falls, it affects Clinton's chances in a significant way.
Registered Republicans expanded their lead this week in Ohio. They're now ahead of Democrats by almost 66,000 votes, or about 5 points. They were only up by 2.5 points one week ago.
This is good news for the Republican Party's chances in Ohio. That's because at this point in 2008, the last year when there is comparable data, Republicans led by a razor-thin margin of 0.4%. And that early vote lead wasn't enough for them to ultimately carry the Buckeye State that year.
Early voting is down across Ohio this year. That's likely the result of cutbacks, imposed by the Republican-controlled legislature in 2013, to the number of days of early voting.