Trump: Why didn't protesters vote?

President Donald TrumpDonald TrumpTrump to meet with Bill Gates If Trump kills public broadcasting, America loses Trump to oldest living Pearl Harbor vet: 'Keep going!’ MORE on Sunday raised questions about whether protesters who marched in Washington and around the nation a day earlier voted in the presidential election.

"Watched protests yesterday but was under the impression that we just had an election!" the president tweeted. 

Watched protests yesterday but was under the impression that we just had an election! Why didn't these people vote? Celebs hurt cause badly.

— Donald J. Trump (@realDonaldTrump) January 22, 2017

“Peaceful protests are a hallmark of our democracy,” he said in a later tweet. “Even if I don't always agree, I recognize the rights of people to express their views.”

Peaceful protests are a hallmark of our democracy. Even if I don't always agree, I recognize the rights of people to express their views.

— Donald J. Trump (@realDonaldTrump) January 22, 2017

At least 3 million protesters on Saturday took to the streets of Washington, D.C. and cities across the world on the first full day of Trump's presidency, according to a review of official and unofficial estimates from the nation's largest cities.

Large turnouts were reported in Boston, New York City, Chicago and Los Angeles as organizers for the main rally and march in Washington, D.C. grappled with a huge number of demonstrators.

Half a million people showed up at the National Mall and nearby streets for the Women's March on Washington.

At the event in Washington, D.C., a number of Democratic lawmakers and celebrities encouraged demonstrators to take action in the wake of a Trump presidency.

Feminist icon Gloria Steinem during the event called for Trump to unite the nation instead of divide it, saying that if the U.S. begins a registry of Muslims, then "we will all register as Muslims."

Sen. Bernie SandersBernie SandersSenate Dems introduce bill to rescind Trump border wall, immigration order Top Dems prep for future while out of the spotlight Perez creates advisory team for DNC transition MORE (I-Vt.) tweeted in support of the marchers. Former Democratic presidential nominee Hillary ClintonHillary Rodham ClintonChelsea Clinton plans new children's book: 'She Persisted' Top Dems prep for future while out of the spotlight New report finds that voter turnout in 2016 topped 2012 MORE also tweeted ahead of the march to thank the protesters.

--This report was updated at 9:38 a.m.