I think a better way to explain it is that up until the Southern Strategy in the '60s, you can essentially think of the Democrats as two separate parties ideologically fused by necessity into one very strange but functional coalition. The northern state Dems were the ones like FDR and Kennedy who you'd associate with the current DNC, relatively liberal (by the standards of their time), while in the south you had Strom Thurmond and George "Segregation today, segregation tomorrow, segregation forever!" Wallace, with the only real shared point being both factions didn't like Republicans.tstorm823 said:Yes. Segregation was popular.Eacaraxe said:Strom Thurmond was a left-winger?
To be specific, Southern Democrats were pro-segregation because the south as a whole was pro-segregation. When the south as a whole turned against segregation, the vast majority of Democratic politicians turned against it following public opinion. Strom Thurmond himself was not a typical Democratic politician, he was actually a ideological segregationist, a coincidental ally of the left in that era, not particularly left himself. But he was a member of the left-wing party.
Or to use one of my favourite oddities in military history for an example, sort of a Battle for Castle Itter [https://www.youtube.com/watch?v=BwfJsKfCnaM] situation. Wherein an improbable motley assortment of US Army, Wehrmacht, local resistance fighters and a bunch of newly-freed French POWs fought together against several hundred Waffen-SS troops who were basically on a standard spree of looting and murdering.