I hear people using the fact that the parties switched as an argument against/for some parties in some political arguments. I don't care about modern politics, but was it politics that caused the USA's Republican and Democratic parties to switch? How long did this transition take, and what time period was it?
This is a popular question. Answers to various versions of this question can be found in the FAQ.
Of particular interest is what /u/erissays wrote in response to "Myth or Fact: Did the US political parties switch platforms?"