American politics has been dominated by the Democratic and Republican Parties since the Civil War. That gives us the illusion of stability — that today’s political divisions cut roughly the same lines as yesteryear.
But in recent decades, the two parties have been changing, and fast. Those changes are ideological — the Democratic Party has moved left, and the Republican Party has moved right. But more fundamentally, those changes are compositional: Democrats have become more diverse, urban, young and secular, and the Republican Party has turned itself into a vehicle for whiter, older, more Christian and more rural voters. CONT.
Ezra Klein, New York Times