The lines were long at polling locations across Texas on the first day of early voting Tuesday, and some of the state’s biggest counties reported record first-day turnout.

But with reliable data from the state still limited on who is showing up to vote so far, it remains too soon to tell whether the trend will continue through Election Day or what it means for Democrats’ hopes to turn the state blue.

According to the state Democratic Party, over 1 million Texans cast ballots on the first day of early voting. Using data from county election supervisors in the state’s largest 10 counties, home to 57% of registered voters in Texas, The Texas Tribune found that at least 425,028 ballots were cast in-person Tuesday, while at least 224,122 had been sent in by mail. The number of absentee ballots is likely to be higher this year than in previous years because of the ongoing coronavirus pandemic.

In 2016, by comparison, 340,006 Texans cast in-person ballots in those 10 counties on the first day of early voting, and 157,277 had cast ballots by mail. That year, the early voting period was shorter by about one week.

From 2016-20, there was a slight increase in the first-day turnout rate in the 10 biggest counties — 5.82% to 6.71%. As of Wednesday, there are 9,678,017 registered voters in those 10 counties. The number is subject to change as counties continue to report registered voters to the state.

The available totals for this year have split observers along party lines: Democrats, who count turning out new voters as their best hope for victory this year, take it as a sign Texas might flip. Republicans say it is par for the course in a competitive election year.

“Right now all we have is one day of early voting under our belts, and we have many more to go, so I’d equate it to a horse race,” said Derek Ryan, a Republican voter data expert. “The Democrats got a good start out the gate, but we’ve still got a whole race to run.”

Harris County, the state’s most populous, had the biggest first-day turnout out of the state’s top 10 counties, according to a Tribune analysis. Nearly 170,000 of the county’s nearly 2.5 million registered voters had cast ballots in person or through mail-in voting as of Wednesday morning. In 2016, by comparison, Harris County had just under 130,000 ballots submitted on the first day.

In Dallas County, nearly 60,000 people had cast in-person ballots, according to a county report. In addition, more than 33,000 submitted their ballots by mail, according to the Texas secretary of state.

But what that means about who will win Texas remains an open question. High first-day turnout can be a sign of new voters going to the polls — or it can be a sign of shifting habits. Are more people voting? Or are the people who would normally be expected to vote simply showing up earlier? Those questions are difficult to answer so early in the process.

The state’s voting numbers were incomplete Wednesday, meaning it was also difficult to tell whether high first-day turnout was being replicated in smaller counties across Texas. The state’s urban centers tend to lean more Democratic, and it’s not immediately clear to what extent there are similar trends in the state’s more rural counties that lean Republican.

Still, Wednesday’s numbers had Democrats excited.

In a statement, the Texas Democratic Party cheered the sheer number of Texans going to the polls and took it as a sign that the state may be in play later this fall.

“Across our state, Texas Democrats are fired up, voting, and ready to win,” said Gilberto Hinojosa, the party’s chair. “The first day of early voting was great but we still know that there is a lot of work to do and plenty of votes to be cast.”

The 10 most populous counties in the state are Harris, Dallas, Tarrant, Bexar, Travis, Collin, Denton, El Paso, Fort Bend and Hidalgo. Mail ballot data for Dallas and Fort Bend counties came from the secretary of state. Other data came directly from the counties.

Early voting runs through Oct. 30. Election Day is Nov. 3.

Disclosure: The Texas secretary of state's office has been a financial supporter of The Texas Tribune, a nonprofit, nonpartisan news organization that is funded in part by donations from members, foundations and corporate sponsors. Financial supporters play no role in the Tribune's journalism. Find a complete list of them here.