The city essentially kicked African Americans out starting in the 1970s under the guise of redeveloping the Fillmore District. Since then, it's been a matter of economics. SF has the smallest % of African Americans of any major US city (6.5%). This is smaller than cities typically thought of as "white:" Minneapolis (17%), Seattle (9%) and Portland, Oregon. (7.9%). Even Portland, Maine has a higher percentage of African Americans (6.6%).
As others have mentioned, Oakland is where African American people live in the Bay Area.
You just need to go across the Bay Bridge. I'm not sure how or when it happened but for some reason San Francisco is very white and Oakland is very black.
As others have mentioned, Oakland is where African American people live in the Bay Area.