Political Parties Can’t Flip Flop?

Seth Masket points out that dramatic shifts are very rare:

The Democrats’ shift from being the party of white supremacy to the party of civil rights was pretty much a singular act in American political history. Parties rarely pull off a major shift on a hot-button issue (that’s what killed the Whigs in the 1850s), and indeed it was a very costly shift for the Democrats, breaking their electoral lock on the southern states and ultimately ending their four-decade run of controlling the House of Representatives. To be sure, parties do evolve slowly on some issues, but the parties are much better defined by consistency than change.