These votes represent almost 43% of registered voters nationwide, according to a survey of election officials in all 50 states and Washington, DC, by CNN, Edison Research, and Catalist.
Fourteen states have already seen more than half of their registered voters cast ballots ahead of November 3.
Nationwide, the more than 90 million ballots already cast represent about 66% — almost two-thirds — of the more than 136.5 million ballots cast in the 2016 presidential election.
About half of the votes already cast this cycle come from those 16 key states, which will play a crucial role in determining who wins the presidency this year.
Some voter information comes from Catalist, a company that provides data, analytics and other services to Democrats, academics and nonprofit issue-advocacy organizations, and is providing insights into who is voting before November.
Supporters of Democratic nominee Joe Biden have shown a strong preference for mail-in voting, while most President Donald Trump’s supporters say they want to vote on Election Day.
Trump and Biden’s schedules in the final stretch of this campaign have reflected the focus on those competitive states.
In the last weekend before Election Day, Trump is spending Saturday in Pennsylvania, while Biden is campaigning in Michigan with former President Barack Obama. Biden then heads to Philadelphia on Sunday, as the President has five rallies planned in five key states — Michigan, Iowa, North Carolina, Georgia and Florida.
CNN’s Veronica Stracqualursi contributed to this report.