California (titular see)

The Diocese of California, a residential episcopal see from 1840 to 1849, is now a titular see of the Catholic Church.

Pope Gregory XVI set up the Diocese of California with the papal bull Apostolicam sollicitudinem of 27 April 1840. He assigned to the new diocese a vast territory taken from that of the Diocese of Sonora, now the Metropolitan Archdiocese of Hermosillo, in Mexico. It included Alta California (corresponding to the present-day American states of California, Nevada, Arizona, Utah, western Colorado and southwestern Wyoming) and the Baja California Territory (the modern Mexican states of Baja California and Baja California Sur). He set the episcopal residence at San Diego and made the diocese a suffragan of the Archdiocese of Mexico City.

After the Mexican-American War, Alta California became United States territory and the Holy See divided the American diocese into US and Mexican sections.

The diocese was nominally restored as Latin Titular bishopric of California or Both Californias (English) / Ambas Californias (Spanish) / Latin adjective Californien(sis)

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