How did big media miss the Donald Trump swell? News organizations old and new, large and small, print and online, broadcast and cable assigned phalanxes of reporters armed with the most sophisticated polling data and analysis to cover the presidential campaign. The overwhelming assumption was that the race was Hillary Clinton’s for the taking, and the real question wasn’t how sweeping her November victory would be, but how far out to sea her wave would send political parvenu Trump. Today, it’s Trump who occupies the White House and Clinton who’s drifting out to sea—an outcome that arrived not just as an embarrassment for the press but as an indictment. In some profound way, the election made clear, the national media just doesn’t get the nation it purportedly covers.What went so wrong? What’s still wrong? To some conservatives, Trump’s surprise win on November 8 simply bore out what they had suspected, that the Democrat-infested press was knowingly in the tank for Clinton all along. The media, in this view, was guilty not just of confirmation bias but of complicity. But the knowing-bias charge never added up: No news organization ignored the Clinton emails story, and everybody feasted on the damaging John Podesta email cache that WikiLeaks served up buffet-style. Practically speaking, you’re not pushing Clinton to victory if you’re pantsing her and her party to voters almost daily.The answer to the press’ myopia lies elsewhere, and nobody has produced a better argument for how the national media missed the Trump story than FiveThirtyEight’s Nate Silver, who pointed out that the ideological clustering in top newsrooms led to groupthink. “As of 2013, only 7 percent of [journalists] identified as Republicans,” Silver wrote in March, chiding the press for its political homogeneity. Just after the election, presidential strategist Steve Bannon savaged the press on the same point but with a heartier vocabulary. “The media bubble is the ultimate symbol of what’s wrong with this country,” Bannon said. “It’s just a circle of people talking to themselves who have no fucking idea what’s going on.”The map at the top of this piece shows how concentrated media jobs have become in the nation’s most Democratic-leaning counties. Counties that voted for Donald Trump in 2016 are in red, and Hillary Clinton counties are in blue, with darker colors signifying higher vote margins. The bubbles represent the 150 counties with the most newspaper and internet publishing jobs. Not only do most of the bubbles fall in blue counties, chiefly on the coasts, but an outright majority of the jobs are in the deepest-blue counties, where Clinton won by 30 points or more.But journalistic groupthink is a symptom, not a cause. And when it comes to the cause, there’s another, blunter way to think about the question than screaming “bias” and “conspiracy,” or counting D’s and R’s. That’s to ask a simple question about the map. Where do journalists work, and how much has that changed in recent years? To determine this, my colleague Tucker Doherty excavated labor statistics and cross-referenced them against voting patterns and Census data to figure out just what the American media landscape looks like, and how much it has changed.The results read like a revelation. The national media really does work in a bubble, something that wasn’t true as recently as 2008. And the bubble is growing more extreme. Concentrated heavily along the coasts, the bubble is both geographic and political. If you’re a working journalist, odds aren’t just that you work in a pro-Clinton county—odds are that you reside in one of the nation’s most pro-Clinton counties. And you’ve got company: If you’re a typical reader of Politico, chances are you’re a citizen of bubbleville, too.The “media bubble” trope might feel overused by critics of journalism who want to sneer at reporters who live in Brooklyn or California and don’t get the “real America” of southern Ohio or rural Kansas. But these numbers suggest it’s no exaggeration: Not only is the bubble real, but it’s more extreme than you might realize. And it’s driven by deep industry trends.