With these enormous caveats out of the way, the fact remains that Americans’ “trust” in “the media” is falling steadily, according to Gallup. Even if the precise definitions of these terms is debatable, the overall decline is clear and noteworthy.

This collapse in trust is not evenly spread across all demographics. The drop has been most dramatic among young and middle-aged respondents and, most recently, within the GOP. Together, it seems reasonable to conclude that the recent decline in media trust has been concentrated among middle-aged Republicans, a key part of the Trump constituency.

What is behind this collapse? Here are four somewhat overlapping hypotheses.

1. It’s the media’s fault.

Certainly, when some people read the headline that trust in the media is falling, their response might be, "yes, and deservedly so."

Although a great deal of excellent journalism is produced every week, it is never hard to find the low-lights. This is hardly a new phenomenon. Twenty years ago in The Atlantic, James Fallows criticized newspaper reporters and the television shows for treating politics like a partisan tug-of-war in which policy issues were reduced to playing the part of the oft-forgotten rope. “The discussion shows that are supposed to enhance public understanding may actually reduce it, by hammering home the message that issues don't matter except as items for politicians to fight over,” he wrote.

Two decades later, many of Fallows’ observations are so fresh they could be auto-tweeted each morning. The last few months, in particular, have seen a bonanza of false equivalence and theater criticism masquerading as political analysis during the election. Beyond the moral rot at the head of Fox News and Trump’s embrace of Breitbart (the Internet’s most crowded den of race-baiting conspiracy theories), even many major newspapers failing to properly cover the candidates’ many flaws. If public trust in the press has gone up in flames, there are more than enough media organizations to be held liable for the arson.

2. It’s the elections’ fault.

As the first graph indicates, American trust in mass media seems to decline around presidential elections. It fell in 2004, and again in 2008, and again in 2012, and now it's collapsed in 2016. Perhaps the hyper-politization of elections, which cleaves the electorate and entrenches two opposing viewpoints on a single national story, erodes public faith that “the media” can be fair to both camps.

This election campaign, however, is exceptional for the fact that Trump routinely so denounces the media for being unfair to him. This would explain why faith in the mainstream press has collapsed among middle-aged Republicans. Trump has even questioned conservative staples like Fox News and the Wall Street Journal, which would explain why we’re seeing an unprecedented drop in faith among the GOP in this election.