When did the parties switch platforms?

[Agonized-Statism]

Aside from the coalitions, which were bound to change anyway as America's demographics and the dynamics of the electoral college shifted wildly, we've generally stuck to the fundamentals. The conservatives benefit from reduced turnout and the liberals benefit from high turnout. The conservatives are the nationalists and the liberals are the "other" (sectionalists and internationalists). The conservative party wants to stick to the Anglosphere and the liberal party wants to pivot to Asia. The conservatives still benefit, more or less, from the Protestant moral panic (although it's a tiny minority at this point) and the liberals are the "freewheeling wets". The conservative party is more for protectionism and the liberal party is more for free trade, although trade is something that changes given the nature of the economy (agrarian, industrial, post-industrial). Despite the cultural division making their positions less apparent ("coastal elitists" and all), the conservatives always have a base with the aristocracy and the bottom of the caste system always carves out a place in the liberal faction. The middle class- the suburbanites- are always swinging back and forth.

They didn't "switch platforms", because we're no longer having debates about whether or not to continue slavery or industrialize. As new debates came up, the parties adopted new issues and the coalitions adapted.

Sure, Lincoln wanted to end slavery. He also wanted to ship the slaves back to Africa and make the US a white ethnostate. And of course Eisenhower stood for the Little Rock Nine. It was for the supremacy of federal power over state power and to give capitalism a human face as the Soviets watched, not necessarily civil rights. The liberal myth that the parties switched places, ensuring a long continuous heritage of "good guys", is another attempt to absolve the country and its institutions of their sins instead of celebrating actual progressive icons like Eugene Debs and Malcolm X.