data californiaTracking California is a program of the Public Health Institute, in partnership with the California Department of Public Health and the Centers for Disease Control's (CDC) National Environmental Public Health Tracking Program. ... We are aCalifornia is a state in United States. The population in California was 39,431,263 in 2025. The median age in California was 37.6 in 2025. The median income in California was $41,901 in