How charges of voter fraud became a political strategy

More common and largely unaddressed, but still rare, are fraudulent mail-in ballots and corruption among election officials.

Fraud charges are a staple of American politics, and once were frequently true. Terre Haute, Ind., was infamous for a 1914 scandal in which the mayor rigged voting machines, bought off voters, registered thousands of nonexistent voters and arrested nosy poll watchers.

But if thievery has not vanished since then, its scope has shrunk markedly: Four Troy, N.Y., officials and party workers were convicted in 2011 of creating false absentee ballots that may have swung local elections. And the next year, Indiana’s chief elections official, Secretary of State Charlie White, was convicted of six felonies involving voter fraud, including submitting a false ballot.

The possibility that fraud or incompetence could change the outcome of a close presidential contest, as some claim happened when John F. Kennedy took the White House on the strength of an 8,000-vote margin in Illinois, is at least conceivable, experts say. But even other Republicans have scoffed at Mr. Trump’s claims that this year’s election could be rigged by voter fraud. Gov. John Kasich of Ohio, a Republican primary opponent, likened them on Wednesday to “saying we never landed on the moon, frankly. That’s how silly it is.”