By Adam Levy, Ethan Cohen and Liz Stark, CNN

(CNN) -- One week from Election Day, early voters so far are younger, more racially diverse and more likely to be Democrats than they were ahead of the 2016 election in many of the key states that could decide the next president.

More than 65.5 million votes have already been cast around the US, surpassing the 58.3 million total pre-election votes cast in 2016. That's almost half of the total presidential votes cast four years ago.

While these are trends that could benefit Democrats, including the party's presidential nominee Joe Biden, they're not predictive of the final results. Polling shows that Republicans are much more likely to say they prefer to vote on Election Day this year, and an early vote counts just the same as one cast on November 3.

Detailed voting information on these key states comes from Catalist, a company that provides data, analytics and other services to Democrats, academics and nonprofit issue-advocacy organizations and is giving insights into who is voting before November.

Here's a look at who has already voted in some of the most competitive states this cycle.

Arizona

Young voters (those between the ages of 18 and 29) make up twice as large a share of early voters in Arizona as they did at this point in 2016. Those voters made up 5% of early voters in 2016; now they make up 10%.

Meanwhile, voters 65 or older have gone from 50% of early voters in 2016 to 41% now.

The share of White early voters in Arizona has dipped slightly from this point in 2016, decreasing from 77% four years ago to 74% currently. Hispanic voters account for the second largest share of ballots already cast at 15%, up from 13% in 2016. Black voters and Asian voters have seen one percentage-point upticks in each of their shares of the early vote as well.

Democrats have overtaken Republicans this year in pre-election ballots cast so far. At this time before the 2016 election, Republicans made up 41% of the ballots cast, with Democrats trailing behind at 37%. Today, Democrats make up 41% of the pre-election vote, with Republicans comprising 34%.

Colorado

In Colorado, where every voter receives a mail-in ballot, the electorate so far is younger than it was at this point in 2016. Then, about 6% of people who had already voted were under 30. Now, that's 11%.

Voters 30-49 also account for more of the ballots that have been cast this year compared to this point in 2016, while voters 65 or older account for a smaller share.

Hispanic voters have expanded their share of the pre-election vote -- 8% last cycle to 10% now.

White voters account for the vast majority of ballots already cast in Colorado, although their share of those ballots has decreased from this time four years from 85% to 83% now.

The Republican share of the pre-election vote is down seven points from a week before the 2016 election, while Democrats are at about the same level.

Florida

Young voters in Florida have almost doubled their share of the votes cast so far compared to this point in 2016. Voters 65 or older made up 50% of the early vote at this time four years ago, but only make up 41% now.

Florida's early voting electorate is slightly more diverse compared to this point in 2016. Both Hispanic voters and Black voters have increased their shares of ballots already cast, with Hispanic voters accounting for about 16% of the early vote (up from 14% in 2016) and Black voters at 13% (up from 12% in 2016).

Democrats are leading in the pre-election turnout with 42% of the ballots cast to the Republicans' 36%. A week before the 2016 election, they were tied at 41% each.

Georgia

Biden campaigns in the Peach State Tuesday, which Trump won by about five points in the last presidential election.

Early voting in Georgia has already surpassed 2016 pre-election voting, and it's reached almost 73% of the total votes cast in the state four year ago.

As in other states, voters under 30 in Georgia account for a larger share of the early vote than they did four years ago. Voters 30-39 have also seen an increase from 9% of the pre-election vote at this point four years ago to 12% now.

Georgia has the largest share of pre-election votes from Black voters of these key states, at 31%, about the same as this time four years ago. White voters' share of the pre-Election Day vote has dropped from 65% in 2016 to 62% currently.

Iowa

More than 750,000 ballots have already been cast, according to Iowa's Secretary of State's office, surpassing the total 2016 pre-election vote. It represents almost half all votes cast in the 2016 presidential election.

Democrats are up significantly in their share of ballots cast so far this year, making up 50% of those ballots. At this time before the 2016 election, their share was 44%. Republicans are currently about the same at 31%.

The age breakdown of early voters in Iowa hasn't changed as much since 2016 as it has in some other states. 10% of the state's early voters so far have been under the age of 30, up only 3 points from this time four years ago. Voters 30-64 also make up a slightly larger share of the electorate compared to 2016. Four years ago, those voters made up 41% of those who had already cast ballots; now they're 47%.

Michigan

2020 is Michigan's first general election since a ballot measure passed to allow anyone to cast a vote by mail, and the age breakdown of the state's early voters has changed dramatically. At this point four years ago, 80% of the state's early voters were 65 or older. Now, those voters make up 46% of those who have cast ballots. Voters under 30 only accounted for 2% of the ballots cast at this point four years ago; now they account for 9%.

While Michigan has already surpassed its total number of pre-election votes cast in 2016, it isn't seeing the same levels of pre-election voting as some other states with longer traditions of early or mail-in voting. So far, voting in the state accounts for almost 44% of the total number of ballots cast in 2016.

Black voters in Michigan have expanded their share of ballots already cast compared to last cycle. They currently account for about 12% of those ballots, up from just 8% in 2016. Hispanic voters and Asian voters have also seen small upticks in their shares of the early vote. White voters' share of the early vote, meanwhile, has dropped from 89% in 2016 to 83% currently.

Minnesota

About 1.2 million ballots have already been cast in the Land of 10,000 Lakes, almost double the state's total 2016 pre-election vote.

Minnesota has seen a large swing in the age breakdown of early voters compared to 2016. Four years ago at this time, 58% of ballots had been cast by people 65 or older. Now, that's 38%.

Voters under 30 have cast almost 143,000 votes so far this year, good for 12% of all ballots cast. That's more than double their share of the early vote at this time four years ago.

Similar to this time last cycle, Minnesota's early voters so far are predominantly White -- 89% now vs. 92% then. Black voters, Hispanic voters and Asian voters have all seen one point increases in their shares of ballots already cast compared to four years ago.

Nevada

Younger voters make up 10% of Nevada voters so far. That's up from four years ago at this time when they made up 6%.

Hispanic voters in Nevada represent the second largest share of ballots cast so far at 13%, slightly up from 12% four years ago. Black voters and Asian voters have also seen one-percentage point increases in their pre-election vote shares. White voters' share of the early vote has decreased slightly from 2016, down from 70% then to 68% currently.

Democrats have held steady with the pre-election ballots cast at 43% -- the same as this time four years ago. Republicans have dropped in their share of the pre-election ballots from 38% back then to 34% now.

North Carolina

In North Carolina, 12% of voters so far are under the age of 30 -- almost double what it was at this point in 2016. Meanwhile, voters 65 and older dropped from 42% of the early vote at this time four years ago, to 33% now.

The breakdown of North Carolina's pre-election voters by race is nearly the same as it was in 2016. White voters account for 72% of those early ballots, Black voters for about 22% and Hispanic voters and Asian voters each for roughly 2%.

Democrats' 10-point lead in pre-election ballots cast is about the same as their 11-point lead at this time in 2016.

Ohio

Voters under the age of 30 have cast about 196,000 votes in Ohio so far, about 9% of the total and up from 6% at this point in 2016. Voters 30-64 increased their share from 41% a week before the 2016 election to 49% now.

By race, Ohio's early voting electorate is similar to what it was four years ago. White voters continue to account for a significant majority of ballots cast so far at 86%. Black voters comprise the second largest share of early voters at 10%, followed by Hispanic voters at 2% and Asian voters at 1%.

Pennsylvania

There is no Catalist data out of Pennsylvania for the last cycle. This year, young voters make up 11% of the more than 1.7 million ballots cast so far in the Keystone State, while 43% are over the age of 65.

White voters in Pennsylvania have cast the majority of pre-Election Day ballots so far, accounting for 82% of those ballots. Black voters represent the second largest share of early voters in the Keystone State at 11%, followed by Hispanic voters and Asian voters each at 3%.

Democrats continue to hold a significant advantage in pre-election voting, making up about 70% of those ballots cast. 2020 is the first year Pennsylvania expanded mail voting options to all voters, and Republicans in the state are expected to vote in larger numbers on Election Day, which would fall in line with polling that shows members of the GOP around the country prefer to vote in-person next Tuesday.

Texas

More than 7.8 million Texans have already voted this year. That's more than the total number who voted before Election Day in 2016 and about 87% of the state's total turnout from four years ago.

Younger voters in Texas are turning out to vote early this year in far greater numbers than at this point four years ago, with more than 850,000 ballots cast. They currently make up 12% of the pre-election vote, doubling the 6% of the share one week before the 2016 election.

Texas is one of the only key states where Black voters' share of ballots already cast has slightly decreased compared to four years ago. At this point in 2016, Black voters represented 15% of the ballots already cast; now they're at 13%. Hispanic voters continue to comprise the second largest share of those early voters at 20%, on par with 2016 levels.

White voters comprise 61% of the early vote, the smallest share of all the key states listed here. That number is about the same as it was at this time four years ago.

Wisconsin

More than 1.3 million people in Wisconsin have already voted -- almost half of the state's total 2016 presidential vote.

Wisconsin has seen a significant drop in the share of early voters who are 65 or older compared to this point in 2016. Four years ago, 52% of early voters were 65 or older. Now, those voters make up 38%.

In Wisconsin, the current racial composition of those who've already voted is almost identical to what it was at this point in 2016. White voters account for 89% of ballots cast, followed by Black voters at 5%, Hispanic voters at 3% and Asian voters at 2%.