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.
Luding County, located in the southeast of Ganzi Tibetan Autonomous Prefecture in Sichuan Province, is located in the transitional zone from Qinghai-Tibet Plateau to Sichuan Basin, bordering Tianquan and Laojing in the east, Kangding and Kowloon in the west, and Shimian County in the south. The county is 236.2 kilometers away from Chengdu and 49 kilometers away from Kangding. The county seat is 1321 meters above sea level, with 7 towns, 5 townships and 145 administrative villages within its jurisdiction, covering an area of 2165.35 square kilometers. It is inhabited by 17 ethnic groups, including Han, Tibetan and Yi, with a total population of 87065 at the end of 2017. It is a mountainous multi-ethnic county with the smallest land area, relatively high population education, the densest population and rapid economic development. it is also a regional trade center in the eastern part of Ganzi Prefecture and a supply base for agricultural and sideline products in various counties in Ganzi Prefecture. It is known as the "Dongda" of Ganzi Prefecture.