High Quality Content by WIKIPEDIA articles! The Del Mar Union School District is based in Del Mar, California, founded in 1906. For many years, the district was small, serving approximately 1,000 students in the City of Del Mar. However, in the 1990s, the district's boundaries were expanded to include the newly-developed Carmel Valley subdivision in the City of San Diego. Today, approximately 4,000 children attend the district's eight schools.