Donald Trump did a lot of lying during his first weekend as president, inflating the size of his inauguration crowd and denying his prior attacks on the Central Intelligence Agency. But there was one thing that he got right, or nearly so.

“Watched protests yesterday but was under the impression that we just had an election!” Trump tweeted on Sunday. “Why didn’t these people vote?”

Protesters at Saturday’s Women’s March in Washington and at dozens of other rallies across the country were quick to ridicule the remark, noting that people who travel long distances to demonstrations aren’t likely to sit out election day. And they stressed that more Americans voted for Hillary Clinton than for the man who was sworn in on Jan. 20, although Trump — with his characteristically blasé attitude toward the truth — has denied that too.

Yet if you swap out “these people” for “more people,” Trump was onto something. Compared with other democracies, a pathetically small number of Americans bother voting. And the key to stalemating Trump — and to defeating him the next time around — will be getting more people to the polls.

Among the 34 countries in the Organization for Economic Cooperation and Development, the United States ranks 31st in the percentage of eligible voters who turn out to cast ballots. Last November, only 58% of eligible Americans voted. That’s despite the fact that some states have implemented same-day registration — which lets people register and vote simultaneously — and that a growing number of states provide early voting by mail. ...