Established in 1957, our mission is to foster the enrichment of cultural and educational ideas and to link business development between our two cities. To foster and increase the enrichment of cultural and educational ideas. The San Diego-Yokohama Sister City Society was established in 1957 as one of the first sister cities on the west coast. The Society has sponsored numerous exchanges in the field of arts, business, culture, and education between the City of San Diego and the City of Yokohama, Japan.