Election experts, however, say there's another voting method that's proven effective at tallying counts while reducing lines on Election Day: early in-person voting.
Forty-one states and the District of Columbia have rules that allow their constituents to lock in their vote days before Election Day -- even on weekends -- either at in-person polling stations or through in-person absentee submissions.
Wendy Underhill, the director of elections and redistricting for the National Conference of State Legislatures (NCSL), which as part of its mandate provides information on early in-person options, told ABC News that the early-voting system has previously been instrumental in decreasing lines of voters on Election Day.
"I think any election official would be glad to see them come through earlier, especially during COVID," she told ABC News.
Underhill and other experts say they're concerned that some election officials aren't doing enough to promote early in-person voting or expand it to more locations. But they say there's still time for election officials and state leaders to let voters know the option is available.
A rise in popularity
Early in-person voting has been part of some states’ election laws as far back as 1921, when Louisiana and Texas established in-person absentee balloting, according to the NCSL.
Thirty-eight states have approved early in-person voting for at least some of their counties since the 1960s.
Thirteen states allow voters who opt for mail or absentee voting to drop off their ballots at their election office or designated drop-off sites. Some districts count these votes as an absentee ballot in their tallies, according to experts.
Twenty-seven states open up polling sites in some or all of their districts in the weeks before the election and mark the ballots right there and then.
Early voting periods range in length from four days to 45 days before Election Day, with an average length of 19 days, according to the NCSL.
Charles Stewart, a professor of political science at The Massachusetts Institute of Technology, has been studying voting patterns over the last two decades and told ABC News some early voting poll sites and drop-off centers provide voters with better site resources than others. Some sites, particularly ones located in election offices, have full-time employees who have better training and knowledge than volunteers, he said.
"As election laws have become more complicated, having a site run by more permanent staff is really a convenience," he told ABC News.
Stewart's research shows that early voting has been increasing over time.
Between 2006 and 2018, the percentage of national voters who cast their vote at a polling site on Election Day dropped from roughly 80% to roughly 60%, according to voter data. During that same period, the percentage of voters who chose early in-person voting grew from 5.8% to 16.7%, and the percentage of voters who mailed in their ballot increased from 13.8% to 22.3%.
"Voters have been clamoring for greater convenience, and election officials have been looking for ways to create administrative efficiencies," Stewart said.
Michael McDonald, a professor of political science at the University of Florida, told ABC News that aside from mail-in voting, which he emphasized is a valid and reliable method, in-person early voting is crucial in getting the highest turnout in light of the pandemic.
McDonald predicts there will be record turnout during this year's general election, and that early poll sites and drop off locations will "flatten the curve" by taking the pressure off polling places on Election Day.
As evidence, McDonald points to the long lines that were reported during this spring's primaries, like in Wisconsin, where some voters were forced to stand in long lines for hours after election officials reduced the number of polling sites -- especially in more populated cities like Madison.
"Any relief valves you can put into the system can relieve the pressure that you might see on Election Day," McDonald told ABC News. "Even if you see longer lines during in-person early voting, they won't be as long as if we forced people to wait in line on Election Day."
McDonald also said early in-person voting would alleviate concerns from voters who are worried their mail-in ballot won't be received by their election office on time or be disqualified due to a technicality.
"States have been moving to mail balloting, but it is important to have in-person voting options," he said.
Even though more people are turning to early in-person voting, experts say some states have been better than others at getting the word out to the electorate.
Sylvia Albert, the director of voting and elections for the civic advocacy non-profit Common Cause, said for the states that have had early voting for a longer period of time, such as Texas and Florida, early in-person voting has become a standard part of the election cycle and not a novel concept to voters.
"For a lot of them this has been the norm, and they'll be heading to the sites during those hours," she told ABC News.
The media attention surrounding mail-in ballots, which Albert emphasized are just as secure and viable as any ballot cast on Election Day, has shifted the attention from the early in-person option, she said.
Albert said some states that are new to early voting during a presidential election, such as New York and Virginia, haven't been informing their electorate about this avenue.
"Election officials need to be more public about the procedures that allow people to vote during this pandemic," she said.
A representative from the New York State Board of Elections said election districts have submitted plans to roll out a “get out the vote” media campaign that will include press releases, print ads, social media, and other tools that will instruct voters about their options, including early voting.
"The additional nine days of early voting can help reduce the volume of voters seeking to vote in person, as well as provide convenient nighttime and weekend hours," Cheryl Couser, a spokeswoman for the New York State Board of Elections, said in a statement. "Each county has an early voting communication plan in place to inform voters of the locations of their early voting sites and hours of operations."
Most of New York state's election districts will have their media blitzes up and running in September and some, like those in New York City, already offer voter tools to find their early voting locations.
Representatives from the Virginia Department of Elections would not comment on that state's early voting plans.
Carolyn DeWitt, president and executive director of the nonprofit Rock the Vote, acknowledged that some election officials have been slacking this year when it comes to messaging the public. However, she noted that many have been crippled by budget cuts due to the pandemic.
And, she said, the federal government hasn't made a push to help.
"The reality is, even those [election officials] that do care about the integrity of our elections are completely being overwhelmed right now. They're being asked to work miracles with very little," she told ABC News.
McDonald said the pandemic has also hurt in more concrete ways, as election officials struggle to find locations that are willing to be poll sites and drop-off locations.
Many schools and senior centers that were once community staples as polling sites for both early voting and Election Day voting are declining to do so this year over concerns that students, residents and staff will be endangered by large crowds, McDonald noted.
"There is also the staffing issue," McDonald said. "A typical poll worker is over 60, and some people aren't volunteering because they're afraid of the crowds."
He noted that in some districts, early voting poll sites and absentee drop-off centers are in government buildings or larger locations like stadiums, so the coronavirus dangers are not as prominent. But McDonald said states will still need more sites to ensure safety.
A representative for the National Association of State Election Directors told ABC News that election officials in all states have been working to ensure that voters have safe and secure early voting sites. The association has posted guidence on its website from a number of federal agencies, including the Elections Infrastructure Government Coordinating Council and Sector Coordinating Council’s Joint COVID Working Group and U.S. Centers for Disease Control, regarding social distancing and site cleaning at poll sites.
What states are doing -- and not doing -- to expand early voting
Despite the challenges, experts says some state leaders are working to expand early voting's availability.
On Aug. 7, California Gov. Gavin Newsom signed a law allowing counties to offer fewer in-person polling places in exchange for opening the sites earlier. The measure also requires counties to have one ballot drop-off location for every 15,000 registered voters, for 28 days before the election.
In Texas, Gov. Greg Abbott announced last month that his state will extend early voting by an additional week at the beginning of October to help residents cast their vote. Earlier this year, Pennsylvania gave voters who choose mail-in ballots the option of dropping off their ballot in person.
The New York State Board of Elections representative said the board has reached out to the state legislature to request more resources to educate voters on their options.
Underhill said election officials have learned a lot from the primaries and the restrictions required due to COVID-19 -- and they have little excuse for not expanding early voting.
"I'm guessing any election official would focus on this voter's choice message: 'Hey come on and vote early' or 'Hey come on and get your absentee, and we'll process it early,'" she said.
However, at least one state will constrict early voting options.
In June, a three-judge federal appeals panel unanimously re-implemented a Wisconsin law limiting early voting sites to just two weeks before Election Day. The law was initially struck down in 2016 by a lower court judge, but it has been under appeal by GOP lawmakers ever since.
"We do not see a substantive problem with days-and-hours limitations," Appeals Judge Frank Easterbrook wrote in his June decision.
Albert contends that early voting has been proven to alleviate problems on Election Day.
"I don't think early voting is an experiment anymore -- it is a clear, positive way to expand access to the ballot," she said.
With less than three months until the general election, Albert and other experts says there is still time for state leaders to bolster their early voting efforts. Emergency legislation and funding could provide election officials with the tools to find and secure more sites for voters, they said.
Underhill stressed that at the very least, election officials need to advertise and educate their constituents on their early voting options as early as possible.
"It is incumbent on every election official and every elected official to let their constituents know how to vote and where they can to vote," she said.
Stewart predicted that regardless of how states prepare, a large proportion of the electorate will opt to vote before Election Day, and the nation needs to do a better job at handling this demand.
"One of the takeaways from voters in this election is that there are more ways of voting that considered," he said. "We want to create a resilient election system, because this may not be the last pandemic we face in our lifetime."