But what sticks out, when you dig in to the data, is just how dominant the Facebook right truly is. Pro-Trump political influencers have spent years building a well-oiled media machine that swarms around every major news story, creating a torrent of viral commentary that reliably drowns out both the mainstream media and the liberal opposition.

The result is a kind of parallel media universe that left-of-center Facebook users may never encounter, but that has been stunningly effective in shaping its own version of reality. Inside the right-wing Facebook bubble, President Trump’s response to Covid-19 has been strong and effective, Joe Biden is barely capable of forming sentences, and Black Lives Matter is a dangerous group of violent looters.

Mr. Trump and his supporters are betting that, despite being behind Mr. Biden in the polls, a “silent majority” will carry him to re-election. Donald Trump Jr., the president’s oldest and most online son, made that argument himself at the Republican National Convention this week. And while I’m not a political analyst, I know enough about the modern media landscape to know that looking at people’s revealed preferences — what they actually read, watch, and click on when nobody’s looking — is often a better indicator of how they’ll act than interviewing them at diners, or listening to what they’re willing to say out loud to a pollster.