I'd love to learn more.
(1) a sudden rise in SF's black population in the aftermath of WWII (from ~5K residents in 1940 to 43.5K in 1950)
(2) the Western Addition's already diverse racial makeup (relative to other neighborhoods at the time)
(3) the internment of Japanese Americans, which removed ~5K residents from the Western Addition virtually overnight.
But I guess the bright side is what a host to diversity a city can be.