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.
Ludian County is one of the counties under the jurisdiction of Zhaotong City, Yunnan Province, located in the northeast of Yunnan Province, the south of Zhaotong City, the north bank of Niulan River. The east-west horizontal distance of the county is 50 kilometers, the north-south vertical distance is 60 kilometers, and the total area is 1519 square kilometers, of which the mountain area accounts for 87.9 percent of the total area and the dam area accounts for 12.1 percent. As of 2013, Ludian County has jurisdiction over 10 towns, 2 townships (including 2 ethnic townships), a total of 4 neighborhood committees and 80 administrative villages. The county government is in Wenping town. The vertical climate change in Ludian County is obvious, with no extreme heat in summer and no severe cold in winter. The average annual temperature is 12.1 ℃, the annual frost-free period is 220 days, and the average annual precipitation is 900mm. There are silver, lead, copper, sulfur, coal, phosphorus and other mineral deposits, Lemachang silver mine in the territory. Ludian County is the main producing county of wax insects in China, and the main producing county of walnut and high quality flue-cured tobacco in Yunnan Province.