This started happening already in the 1950s before desegregation. The rise of suburbs is directly related to the boom years after WWII and how much development happened outside of cities, where throwing up a new subdivision was much cheaper, and the booming auto industry absolutely loved new demand for commuting.
Also, the FHA and the GI Bill provided cheap loans to buy single use housing for veterans, which were a significant chunk of the population. You can't really get an FHA loan to buy an apartment in a mixed-use building.
(On paper Black people were also entitled to GI bill benefits, but in practice this didn't really happen.) From Wikipedia:
> In the New York and northern New Jersey suburbs about 67,000 mortgages were insured by the G.I. Bill, but fewer than 100 were taken out by non-white veterans.
> the rise of suburbs is directly related to the boom years after WWII
The idea of suburbs was created by Levitt & Sons when building Levittown, PA post-WWII. A neighborhood that had explicit terms that the owners would not sell or rent to non-white people.
