After the ruling of Brown v. Board of Education in 1954, which invalidated segregated-schooling laws, school segregation took de facto form. School segregation declined rapidly during the late 1960s and early 1970s as the government became strict on schools' plans to combat segregation more effectively as a result of Green v. County School Board of New Kent County.[2] Voluntary segregation by income appears to have increased since 1990.[excerpt from https://en.wikipedia.org/wiki/School_segregation_in_the_United_States]

"Limited evidence on school economic segregation makes documenting trends difficult, but students appear to be more segregated by income across schools and districts today than in 1990" [Reardon & Owens (2014) https://sci-hub.st/10.1146/annurev-soc-071913-043152]