With less than a week to go until the US midterm elections, which will determine which party controls Congress for the next two years, more than 43 million Americans have already voted.

Data from the University of Florida Election Lab indicates that four to five million early votes have been cast each day, representing a much higher rate than in most previous elections.

Texas has seen the highest above-average turnout rate so far, says Prof Mike McDonald, who runs the Election Lab database. Hispanic communities are also seeing a much higher turnout than usual.

Overall turnout appears on track to outpace 2020, or even 2018, which beat the 1914 record for overall turnout in a midterm election.

Texas has already surpassed its 2022 numbers by around 1.75 million voters, says McDonald. More than 5.8 million ballots have already been cast in the Lone Star state, which has emerged as a key battleground that could decide which party controls the Senate for the rest of Donald Trump’s presidency.

Data from states that require voters to register a political affiliation indicates an increase is votes cast by Democrats, while Republican early voting numbers remain generally similar to 2022.

Early voting is also up among voters who chose to not register with a specific party, McDonald says, however the data does not show which candidates they chose.

Figures on Thursday, external show that 44% of early ballots have been cast by Democrats, and 31.2% by Republicans. A further 24.7% were attributed to voters who had no party affiliation. However, that’s just for the roughly half of states that require voter affiliation.

Three states require voters to submit their race when they register – North Carolina, Georgia and Florida. Data from these states shows an increase in votes cast by Hispanic and black communities, while voting among white people is on par with 2022 early voting figures.

“That makes sense because communities of colour are more frequently part of the Democratic coalition, and whites are more frequently part of the Republican coalition,” McDonald says.

Texas does not require voters to provide party affiliation or race. But the data still shows a surge in voting by some counties on the border with Mexico, which are comprised of more than 90% Hispanic people.

“When I look at those counties, what I see is some of them are going to beat their 2022 turnout in just the early vote alone,” says McDonald.

Early voting has boomed in recent years, driven by the Covid pandemic when more states began offering early voting options, including both in-person and by mail.

In the 2020 election, when voters were picking both the next president as well as their lawmakers, more than two-thirds of all ballots were cast early. Half of those early votes were also cast by mail.

Voters increasingly prefer to vote in-person, even when voting early, says McDonald. They are also returning their ballots earlier than in previous elections.

He adds that he believes this could be due to concerns about postal voting, but says there is not data to indicate what could be causing this. Postal votes are more likely to be disqualified due to errors, he notes, and says some voters could be concerned about meddling in the US Postal Service.

Early voting will taper off, as states start cutting off early voting as an option in the days before the election on Tuesday, 3 November.