That was more due to the excesses of the Industrial Revolution, not so much the civil war. Part of the reason why the Courts were so necessary to make headway in Civil Rights was because Southern Democrats were so essential to FDRs New Deal coalition and it’s hold on power. Like Republicans today, Northern Democrats were too addicted to power to want to piss off Southerners over social justice issues. Only as the movement gained momentum in the courts and at the grassroots level were (Northern) Washington Democrats finally dragged along. But the regional schism that they had long feared occurred as the filibuster to the Civil Rights Act fell along REGIONAL lines (not partisan one as the culture warriors like to lie about). The schism wasn’t completed until the Democratic Convention in 1968. And Progressive (and mainly Northern and educated) Democrats literally fought with Conservative (mainly Southern and working class) Democrats over the Vietnam War. As Chicago police “rioted” against war protestors in the streets and before national news cameras. It’s why calling someone a “liberal elite” was such an effective ploy for 30 years as conservatives leveraged old conflict and old resentments to effect, The same conflicts and resentments Trump rode into office (“left wing”). As Make America Great Again was a dog whistle —bordering on a racial cat call ——to older and working class white makes who yearn for a return to a 1950s social order and the status that being white and male had back then. A status that is evaporating today.