Early voting continued to soar beyond historical levels throughout the country Friday, with Texas blowing past its total turnout from the 2016 election and nearly a dozen other states closing in on the same milestone.

With four days left until Election Day, more than 9 million people have cast their ballots already in Texas, according to the secretary of state’s office — an unprecedented number for the Lone Star State, where broad get-out-the-vote efforts, shifting demographics and a tightening presidential race have energized the electorate. In 2016, the total turnout in Texas was just shy of 9 million.

Nationwide, the number of Americans who have voted early has passed 86 million, according to tracking by the nonpartisan U.S. Elections Project, exceeding 60 percent of the total turnout from the last election and essentially guaranteeing that Nov. 3 will mark the first election in U.S. history in which the majority of ballots will be cast before Election Day. If the trend continue, the country could be on pace to exceed 100 million votes before Tuesday.

“The early returns, driven by mail ballots primarily, are incredible and are aligned with the historic interest in this election,” said Amber McReynolds, a former Denver elections director and head of the nonprofit National Vote At Home Institute. “I believe most ballots by far will be cast before Election Day, with mail ballots making up the majority of votes this year.”

McReynolds added that the largest group of ballots are typically returned in the final five days of the election, meaning the increases were likely to continue through Monday.

As of Friday afternoon, more than 30 million people in all states and territories had voted in person, and more than 55 million mail ballots had been returned, according to data from the Elections Project, which tracks early voting.

Another 36 million mail ballots remained outstanding, down from roughly 42 million on Wednesday. Election officials say it’s likely that many of those ballots were requested by voters who changed their minds and decided to vote in person.

In the 20 states where party affiliation was available, Democrats made up the bulk of the surge, with more than 19 million having already voted. About 12.3 million Republicans and 9.5 million people without party affiliations have cast ballots, according to the Elections Project.

Texans flocked to polling centers when early voting began in the state on Oct. 13, forming long lines that stretched for blocks in some places.

A spate of election-related lawsuits has complicated early voting there, with the Texas Supreme Court this week upholding the governor’s authority to limit the number of drop-off locations for absentee ballots to one per county. But counties throughout the state have posted record early-voting turnout.

In Harris County, the state’s most populous and home to Houston, nearly 1.4 million people have already voted in person or by mail — the highest voter turnout in any election in the county’s history.

The Democratic-leaning county has taken sweeping steps to boost participation, tripling the number of its early-voting locations, running early-voting campaigns, and offering drive-through voting, in which Texans cast ballots from their cars on portable machines. The county also opened 24-hour voting sites Thursday morning that stayed open through the night and were set to close at the end of early voting Friday evening.

“What we’re seeing is what happens when you invest in lowering the barriers to safe and secure voting as opposed to investing time and effort in building obstacles,” Harris County Judge Lina Hidalgo, the county’s top executive, told CNN’s “New Day” in an interview Friday.

Hidalgo, a Democrat, noted that a million voters in Harris County still hadn’t cast ballots. “It’s a very, very exciting time for the largest county in Texas — our county — for the state as a whole, and I think for the nation,” she said.

Statewide, Texas voter turnout has topped 53 percent. More than 8 million Texans have voted early in person, and more than 947,000 have voted by mail, data from the secretary of state’s office shows.

The explosion in turnout could ease the burden on election officials in dealing with lines, equipment glitches and other potential problems that could arise on Nov. 3, experts said.

“One of the terrific things about people voting before is it will reduce pressure on the election system on Election Day,” said Mark Lindeman, interim co-director of Verified Voting, a nonpartisan election security organization. He compared the early turnout to the goal of “flattening the curve” in the coronavirus pandemic to avoid overloading hospitals. “That’s exactly what Texas has done. Those early voters — they’ve benefited themselves and the people behind them.”

The only other state to exceed total 2016 turnout so far is Hawaii, where 457,000 people have cast ballots to date.

But others could approach that threshold soon. In 10 states — including the battlegrounds of North Carolina, Arizona, Florida, Georgia and Nevada — early voting has surpassed 80 percent of the total turnout from 2016, data from the states and the Elections Project shows.

In North Carolina, where Democratic presidential nominee Joe Biden leads President Trump by 5 percent, more than 4 million people have voted early, nearly 90 percent of the turnout from the last election. Damon Circosta, the Democratic chairman of the North Carolina State Board of Elections, said he expects the figure to climb past 100 percent in the coming days.

“Five months ago, my biggest fear is we weren’t going to be able to recruit enough poll workers to keep the funnel of democracy wide open,” he said. “Watching Republicans and Democrats, older people and younger people, step up to help make sure their fellow citizens can vote is what makes the late nights and long meetings worth it.”

The advantage for Democrats among those who have already cast ballots continued to narrow in North Carolina and Florida this week. In North Carolina, registered Democrats accounted for 38 percent of votes cast compared to 32 percent for Republicans as of Friday, down from 17-point margin after the first week of early voting.

The story is starker in Florida, where Democrats held a commanding margin of about 470,000 votes among mail voters at the start of in-person voting on Oct. 19. On Friday morning, that margin had shrunk to roughly 164,000.

The data in North Carolina also show that the share of those who have cast ballots so far who are Black has ticked downward since the start of early voting — and is now lower than the 2016 rate. After a week of early voting, Black voters accounted for 22 percent of ballots cast; now the figure is 20 percent. In 2016, Black voters accounted for 23 percent of the overall vote in North Carolina.

Mail service remained sluggish in key swing states, causing ballots to arrive late in some places.

This week, as the U.S. Postal Service scrambled to deliver mail-in votes by state deadlines, the on-time rate for ballots in postal districts across 10 battleground states stood at 89.1 percent — 5.9 percentage points lower than the national average.

In the Detroit area, fewer than three quarters of ballots were making it to election offices on time over the past five days, according to Postal Service data. Across the rest of Michigan, about 84 percent of ballots were arriving on time. The figures were similar in North Carolina, where about 85 percent of ballots were arriving on time.

In heavily Republican Butler County, Penn., officials were still working to track down thousands of ballots that were never delivered to the voters who requested them. Local election officials have blamed the Postal Service, though the agency denied there were any significant delays in the area. The return rate for mail ballots remained below 25 percent in the rural jurisdiction of 187,000, by far the lowest of any county in the state.

Addressing the problem in a news conference Friday, Jonathan Marks, the state’s deputy secretary for elections, said the Postal Service was collecting additional information from the county to try to identify where the ballots may have entered the mail system. Postal Service staff have also swept post offices in Butler County and a distribution center in Pittsburgh, he said.

Secretary of State Kathy Boockvar said voters who have not received their ballots should go to their county board and get a replacement ballot, or plan to vote in person on Election Day by provisional ballot.

“They all met the application deadline,” she said, “so there’s not a deadline issue.”

Jacob Bogage contributed to this report.