America is becoming extremely efficient at creating superclusters of like-minded citizens. White evangelicals famously delivered 81% of their 2016 votes to Donald Trump. Manhattan gave 87% of its vote to Hillary Clinton. She won 91% of the vote in Washington, D.C., and 84% of the vote in San Francisco.

Almost 80% of Americans live under unified, one-party rule. A total of 36 states–15 Democratic and 21 Republican–have “trifecta” governments where one party controls the upper house, the lower house and the governor’s mansion. Minnesota is the only divided legislature in the entire U.S.

Moreover, states where red and blue dominate are not scattered randomly across the map. The West Coast and New England are bastions of blue rule. The South and large sections of the upper Midwest represent the red heartland.

Now, let’s throw in another ingredient–enmity. It is clear that partisan Americans dislike each other a great deal. We live separately, snarling at each other across a growing divide. The result is a politics of fear and rage, where policy differences often take a back seat to the list of grievances that red possesses against blue and blue against red.