I grew up in segregated Indianapolis ~ that ended about 1950 when I was still a little kid, but my grandmother used to take me downtown and back and we'd sit in back of the bus with the black people, and she'd dare the drivers to bust her.
Back when her and my grandfather first moved to Naptown the KKK ran the state. The house they bought had been owned by a KKK guy and the coal box basement was filled with his KKK literature. She said she enjoyed using it to light the furnace in the mornings!
Years later I discovered the murdered girl named Madge Oberholzer had lived in our neighborhood ~ her death ignited a shock wave of public indignation that destroyed the KKK in Indiana. Later on, DC Stephenson, their former leader got out of jail and they moved him to Seymour, Indiana for his parole. My other grandmother, a staunch Republican voter, hit the ceiling on that. She didn't even believe DC should have walked out of the courtroom alive and there he was where she had to see him on the public streets.
Desegregation occurred first in the North ~ in the Midwest where it'd been as enshrined in law as it had been in the South.
That spread to the Mid-South, then the Deep South.
Along the way there were some burned out buses, murdered young people, laws changed, riots held, verbal exchanges passed around ~ and in the end the Republican and Democrat parties were forever after changed and in surprising, totally unexpected ways.
The only law Missouri had pertained to Schools. Segregated schools were the law. The other Jim Crow laws didn’t pertain as far as I know.
Certainly not while I was growing up. There was a time when St. Louis schools were considered a model for desegregation. Then came the unwritten policy of redlining.
Real Estate Agents redlined certain areas so that blacks were concentrated in certain areas and whites in another. Defacto/real segregation.
Next you had the Courts enforced busing.
The state of Missouri was split during the civil war. The confederate sympathizers were routed from Jefferson City and ran to the area around Neosho, and claimed that they were the legal government.
Another government was elected to replace them in Jefferson City that was pro Union. The person in charge of the forces in Missouri, appointed by Lincoln, made some statement to the fact that he would rather see every man, woman, and child in Missouri dead than have the state betray the union.
And of course the civil war started unofficially early along the Kansas/Missouri border.