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.
Yuzhong County, under the jurisdiction of Lanzhou City, Gansu Province, is located in the central part of Gansu Province, near Qilihe and Chengguan District to the west, Anding District of Dingxi City to the east, Lintao County to the southwest, Pingchuan District of Baiyin City to the north, and Jingyuan County and Huining County to the northeast; it is high in the south and low in the middle, with a temperate continental climate, with a total area of 3301.64 square kilometers, and has jurisdiction over 8 towns and 15 townships. In 2017, there are 13 ethnic minorities with a registered population of 469083. Yuzhong County passes through the ancient Silk Road in three ways. Xinglong Mountain is a national 4A scenic spot and a national nature reserve. Qingcheng, an ancient town, is listed as a "national historical and cultural town" because of its historical and cultural relics and the ancient buildings of the Ming and Qing dynasties. The traffic in the county is more developed, such as Lanxin second Line, Lanyu Railway, Baolan passenger Special Railway, etc.