Postal voting in the United States, also known as mail-in voting or vote by mail, involves sending a ballot to a registered voter's home, which is then returned by mail or dropped off in-person, a method shown to increase voter turnout and reduce staffing needs at polling centers. While concerns about fraud exist, actual instances are extremely rare, with experts worrying more about legitimate ballots being rejected on technicalities than about criminal activity. As of 2022, eight states (California, Colorado, Hawaii, Nevada, Oregon, Utah, Vermont, and Washington) allow all elections to be conducted by mail, with five of those holding elections "almost entirely by mail," while 33 states and the District of Columbia offer it as an option—a practice that began with military use in the Civil War, expanded to civilians with Vermont's 1896 law, and reached 42 states by 1938. During the 2020 presidential election, President Donald Trump repeatedly made false claims of widespread fraud, threatened to block Postal Service funding to ensure ballots would be processed on time, and a Homeland Security intelligence bulletin warned that Russia was amplifying criticisms of mail-in voting to undermine public trust. In June 2026, a Republican-led effort to bar mail-in ballots from being counted after election day was struck down by the U.S. Supreme Court, though the controversy has sparked ongoing debates about voter access and election security.