White to Non-White Racial Dissimilarity (5-year estimate) Index for San Mateo County, CA was 40.78% in January of 2022, according to the United States Federal Reserve. Historically, White to Non-White Racial Dissimilarity (5-year estimate) Index for San Mateo County, CA reached a record high of 44.70 in January of 2009 and a record low of 40.72 in January of 2021. Trading Economics provides the current actual value, an historical data chart and related indicators for White to Non-White Racial Dissimilarity (5-year estimate) Index for San Mateo County, CA - last updated from the United States Federal Reserve on May of 2024.