Legal segregation never went away, it's just not necessarily Plessy v. Ferguson obvious anymore.
There was a great episode of Why is this Happening about two years ago with Nikole Hannah-Jones, who you might know as the NYT's Pulitzer Prize-winning journalist behind the 1619 Project, that covered this topic: https://www.nbcnews.com/think/opinion/investigating-school-s...
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Sidebar: if you haven't seen Nikole Hannah-Jones's 1619 Project, now is the perfect time to familiarize yourself with it.
Here's the main site: https://www.nytimes.com/interactive/2019/08/14/magazine/1619...
And here is the incredible podcast: https://www.nytimes.com/2020/01/23/podcasts/1619-podcast.htm... — if you only have time to listen to one episode, try the third one, "The Birth of American Music".