San Diego (/ˌsæn diˈeɪɡoʊ/ SAN dee-AY-goh, Spanish: [san ˈdjeɣo]; Spanish for 'Saint Didacus') is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the eighth most populous city in the United States and the seat of San Diego County, the fifth most populous county in the United States, with 3,338,330 estimated residents as of 2019. The city is known for its mild year-round climate, natural deep-water harbor, extensive beaches and parks, long association with the United States Navy, and recent emergence as a healthcare and biotechnology development center. San Diego is the second largest city in the state of California, after Los Angeles.
Tongguan District, which belongs to Tongling City, Anhui Province, is located in the southwest of Tongling City, named after Tongguanshan. East and southeast even the suburbs, west and Congyang County across the river, north Tongling County. The total area is 135 square kilometers. Tongguan District is the north gate of "two mountains and one lake", scenic spots-- Huangshan, Jiuhua Mountain and Taiping Lake, which gathers scientific and educational resources such as Tongling College, Tongling Vocational and Technical College, and Party School of the Municipal CPC Committee. It is the forward position and important carrier for Tongling to implement the strategy of "expanding from north to east". The cultural and natural landscapes include Tianjing Lake, Tongguanshan and Wumushan, which are national 4A tourist scenic spots. In 2018, Tongguan District has jurisdiction over 2 streets and 2 towns, and has another development zone with a resident population of 407000, achieving a GDP of 45.39469 billion yuan.