Mail balloting originated as a mechanism to allow military voters to participate in our elections. During the Civil War, its adoption allowed 150,000 Union soldiers to vote “absentee” from the battlefield. By World War II, all states allowed soldiers to use mail ballots. Today, all overseas voters can request mail ballots on a permanent basis, without having to make additional requests for each election. Military and overseas voters can even cast a backup mail ballot — the federal write-in absentee ballot — if the original ballot does not arrive in time.
In the 21st century, mail ballots have become increasingly prominent in American elections. Since the 2010 federal elections, roughly one out of every four ballots cast have been mail ballots, and a growing number of voters have chosen to vote by mail. Since 2000, more than 250 million votes have been cast via mailed-out ballots in all 50 states.