Is America’s media divide destroying democracy?

Sometimes it seems as if the deepest divide in American politics is not so much between Republicans and Democrats as between voters who watch Fox News, and those who don’t.

For instance, 84% of Fox-viewing Republicans support President Donald Trump’s declaration of a national emergency to build a border wall, according to a March Navigator Research survey. But among the rest of America – including members of the GOP who don’t watch Fox – only 21 percent think the emergency is a good idea.

Splits like this have led to...