The four Bay Area counties who accounted for the largest share of Black residents in 1960 had the lowest share of Black residents who identified as multiracial in 2020.

Share of the Bay Area's Black residents by county, 1960 vs. 2020, and the countywide share of Black residents who identify with another racial/ethnic group, 2020

Table with 5 columns and 10 rows.
Alameda46%35%26%17%
San Francisco30%10%11%24%
Contra Costa10%22%22%24%
Solano5%13%10%19%
San Mateo4%5%7%37%
Santa Clara2%11%14%29%
Marin2%2%2%34%
Sonoma0%2%5%50%
Napa0%1%1%35%
9-County Bay Area100%100%100%23%