Since when does a weekend gathering of “nearly 275” white nationalists in a country of more than 320 million people warrant front-page coverage in major newspapers? Since the election of Donald Trump, apparently.

The same media outlets that insisted Mr. Trump wouldn’t beat Hillary Clinton have spent the past two weeks misleading the public about why he did. Breathless coverage of a neo-Nazi sideshow in the nation’s capital—where antiracism protesters almost outnumbered attendees, according to the Washington Post—helps liberals illustrate their preferred “basket of deplorables” explanation for Mrs. Clinton’s loss.

The reality is that Mr. Trump didn’t prevail on Election Day because of fake news stories or voter suppression or ascendant bigotry in America. He won because a lot of people who voted for Barack Obama in previous elections cast ballots for Mr. Trump this time. In Wisconsin, he dominated the Mississippi River Valley region on the state’s western border, which went for Mr. Obama in 2012. In Ohio’s Trumbull County, where the auto industry is a major employer and the population is 89% white, Mr. Obama beat Mitt Romney, 60% to 38%. This year, Trumbull went for Mr. Trump, 51% to 45%. Iowa went for Mr. Obama easily in 2008 and 2012, but this year Mr. Trump won the state by 10 points. Either these previous Obama supporters are closet racists or they’re voting on other issues.

“Trump switched white voters in key states who were blue-collar primarily—coal counties, manufacturing counties,” the Republican strategist Whit Ayres told me this week. “These are blue-collar whites who voted for Barack Obama. And that’s a very uncomfortable thing to admit by the left. It’s much easier to say a ‘basket of deplorables’ elected Trump. But I’m sorry, that just does not conform to the data in those states that made a major swing from one party to the other.”

Part of Mr. Trump’s strategy was to turn out lots of Republicans who stayed home in 2012, but the president-elect appears to have won white voters by a margin similar to that of Mr. Romney. However, Mr. Trump was able to muster an Electoral College majority by taking advantage of lax support for Mrs. Clinton in the metro areas of large, consequential states like Pennsylvania, Michigan and Wisconsin. That the Democratic nominee failed to speak to the concerns of Obama voters is not the fault of the alt-right.