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.
Ningshan County, which belongs to Ankang City, Shaanxi Province, is located at the southern foot of the middle part of Qinling Mountains, northwest of Ankang City, Zuoshui County and Zhenan County in the east, Shiquan County, Hanyin County and Hanbin District in the south, Foping County in the west and Changan District, Zhouzhi County and Changyi District in the north. Between latitude 33 °7 "11"-33 °50 "38" north and longitude 108 °2 "33"-108 °56 "48" east, it is more than 130km long from north to south and 110km wide from east to west, with a total area of 3678 square kilometers, making it the largest county in Ankang City. The name of Ningshan comes from the "Ningshan Hall" set up in the Qing Dynasty, which means "peaceful Shaanxi". It belongs to the northern subtropical humid climate, which is the transitional zone between the north and south of China and the watershed of the Yangtze River and Yellow River systems. It is the green barrier of the south pillow in Xi'an, the capital of Shaanxi Province, and the north of Ankang.