"Don't wait until election day," Pennsylvania Governor Tom Wolf implored voters this week.
"Hand-delivering your own ballot now will give you the peace of mind that your vote will be counted, and your voice will be heard in this historic election."
Combined with early, in-person voting, at least 71.5 million votes have already been cast, more than the total number of advance votes four years ago.
Many states made it easier to request a mail ballot this year amid the coronavirus pandemic and concerns about crowded polling places on election day.
One challenge has been ensuring that voters who are not used to voting absentee return their ballots in time to be counted.
Compounding concerns are mail delivery delays that have persisted across the country.
Delivery data from the US Postal Service does not offer much assurance that these ballots will reach their destinations if they have not already been mailed.
Throughout the northern autumn, as ballots moved through the postal system, the agency has consistently missed its goal to have more than 95 per cent of first-class mail delivered within five days.
In the week that ended October 16, the most recently available weekly figures, the Postal Service reported a national on-time delivery rate of 85.5 per cent. Postal districts in many presidential battleground states failed to reach even that mark.
The district that covers the eastern part of Michigan, which includes Detroit and its suburbs, has had one of the country's worst delivery rates — just 71.5 per cent of first-class mail was on-time in mid-October.
Michigan's top election official was among those warning it was too late to try to return a ballot in the mail. She urged voters to use an official drop box or to return their ballot in person at their local election office.
"We are too close to election day, and the right to vote is too important, to rely on the Postal Service to deliver absentee ballots on time," Michigan Secretary of State Jocelyn Benson said.
This year, Michigan has deployed hundreds of drop boxes across the state. The state's ballot deadline is 8pm local time on election day.
The same deadline holds for Wisconsin, after the US Supreme Court rebuffed a Democratic effort to extend it. In the state's April primary, some 80,000 ballots arrived after election day.
Voters in the state appeared to be heeding the call to return ballots early, with only about 287,000 ballots outstanding out of some 1.8 million that were sent. That amounts to roughly 16 per cent yet to be returned.
Nevada voters have more time to return their ballots, which are not due until November 10 if postmarked by election day.
There, an estimated 962,000 ballots were still outstanding as of today, although it's unlikely all those will be returned because the state decided to send a ballot to all 1.7 million active registered voters in the state. Some voters will choose to show up at the polls or just not cast a ballot.
In Florida, four million of a record six million mail-in ballots requested had been returned as of today. The state was on pace to eclipse the return rate of 2016, when 81 per cent of 3.3 million requested mail-in ballots were returned.
To be counted in Florida, ballots must be received by 7 pm local time on election day.
"We are not necessarily concerned about the number of outstanding vote-by-mail ballots, other than trying to hammer home the message that postmarks will not count, and to get them in our office by election day," said Danae Rivera-Marasco, spokeswoman for the Orange County supervisor of elections.
Some voters are still waiting to receive their ballots.
Abby Leafe, a registered Democrat who lives in suburban Philadelphia's Bucks County, checked her mailbox yesterday in vain for her ballot. She hopes to vote absentee but will go to the polls if she has to.
"Making sure we have free and fair elections is worth getting Covid for," said Leafe, a 46-year-old market researcher from Newtown.
In Pennsylvania, the crush of mail-in votes is a record, more than 10 times the number received by counties in 2016′s presidential election.
The current deadline for ballots in Pennsylvania to be received is three days after the election, but last-minute litigation could move that deadline to election day.
In most states, voters who requested an absentee ballot but did not receive one in time or decided not to return it can still show up at their local polling place on election day and vote.
- AP