Secondly, the party switch is a well-documented event throughout 20th century US history/politics. In fact, it can be easily seen visually by simply looking through the voting maps over the last hundred years, as the historically red and blue states gradually switched to the opposite parties. In the early 1900s, both the Republican and Democrat Parties were not that different from each other, and it was common for politicians to flip flop between the two, until after the Great Depression, when the southern Democrat's more Liberal president FDR passed the New Deal to help pull us out of our bad situation, which prompted the northern Republicans to take a more conservative approach to separate their ideologies. This escalated until the Civil Rights Movement in the 60s, when Democrat president LBJ passed the Civil Rights Acts. This caused the racial tensions within the Democratic Party to snap, in which the pro-Civil Rights voters/politicians stayed with the Democrats, and the anti-Civil Rights voters/politicians (most of which were in the southern Jim Crow states) left to form the Dixiecrat Party, which was incredibly supported by the KKK and white supremacists who were against racial equality. The Republicans came up with a strategy to draw in as many of the southern Dixiecrat voters as possible into the now-conservative Republican Party, by using their anti-Civil Rights policies and "state's rights" rhetoric, called the Southern Strategy, which ended up successfully absorbing the Dixiecrat Party into the Republican base (which is also why the KKK and white supremacist groups today overwhelmingly support and endorse the Republican Party). This was the fundamental "party switch" until it was finally cemented by the neoliberal conservative Reagan administration, which began the modern duopoly we have today.

Granted, I hate both the Democratic and Republican Parties, and they both engage in ridiculous identity politics instead of actual class issues that advance the material conditions of the people.