I touched on some of that earlier. I’m curious, however, on your statement here: “When the Republican Party became conservative, most of the original abolitionist families left and became Democrats.” What time frame are you referring to here ? Terms of “Liberal” and “Conservative” by 19th century standards are not how they are today.
Through the late 60’s, both parties had left and right wings. That changed in the 70’s. The South left the Democrat Party, but then the Democrat Party began to run conservatives out of their party. The Republicans were much slower to do that, but over time liberals weren’t welcome.
When I first came to Kansas in the late eighties, the Senators were Republicans, but the House was split between Democrat and Republican and the Governor was a Democrat.