As the United States prepares to hold a presidential election in the midst of a deadly pandemic, many states are relying on voting by mail to reduce in-person contact at the polls, including Colorado.

Colorado has, since 2013, been a universal vote-by-mail state, meaning that it sends ballots directly to all active voters whether they request one or not. As other states have moved to the system during the coronavirus pandemic -- including New Jersey and Nevada, both of which have been sued by the Trump campaign -- there have been concerns of fraud and difficulty verifying ballots, especially in states just now adopting universal vote by mail. But Colorado's system has been successful, especially during the pandemic, according to Secretary of State Jena Griswold, a Democrat.

"In midst of the COVID-19 pandemic, Colorado just set a record turnout for a state primary. A total of 99.3% of voters cast a mail ballot, and there were not lengthy lines or wait times reported at in-person voting centers,” Griswold said in early July. “Despite misleading attacks, disinformation and attempts to make vote by mail a partisan issue, Colorado’s election proves that mail ballots are the key to accessible voting during this health crisis.”

WHAT'S THE DIFFERENCE BETWEEN ABSENTEE VOTING AND UNIVERSAL VOTE-BY-MAIL? 

Counties will begin sending voters their mail-in ballots on Oct. 9, according to Griswold's office. Voters can return their mail-in ballots via the post office, or they can use one of the state-provided drop boxes. Griswold announced that there will be 368 such drop boxes in Colorado -- a 33% increase from the number that was available in 2018.

The drop boxes, according to Griswold, are emptied at least once per day "by a team of bipartisan election judges who maintain a detailed chain of custody log."

Colorado also provides in-person voting options until 7 p.m. on Election Day. Voters can turn in their unused mail-in ballots to a polling place and vote on an in-person ballot, but it is also possible to vote in person without turning in a mail ballot.

"Once you vote in person your county clerk will not accept for counting any ballot that was mailed to you," the Colorado secretary of state's website says.

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Voters choosing to vote in person in Colorado must bring identification.