Workers sort mail-in ballots in October 2024 in San Jose, Calif. The U.S. Supreme Court has agreed to take a case that could require mail ballots to arrive by the close of polls on Election Day.

During the American Civil War, tens of thousands of soldiers used a simple envelope to cast their ballot from the battlefield.

Derrin Robinson has worked in Oregon elections for more than 30 years, long enough to remember when voters in the state cast their ballots at physical polling sites instead of by mail. As the ...