One of the reasons Northbrae, Berkeley is so white and is currently at 1% Black population is because the developer pioneered single-family zoning restrictions in Berkeley. It worked. In all the ads he brags about how the "restrictions" maintain the "character" of the hood.

The developer who built this part of North Berkeley also developed Claremont. Bragging about the superiority of both districts, he says it's the restrictions on home building that ensures the steady rise of property values.

Northbrae 1% Black vs Claremont 0% Black

Anyways you can read more about the origins of single-family zoning originating in these two affluent Berkeley neighborhoods by developers and speculators for free here:
https://escholarship.org/uc/item/26b8d8zh