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.
Longtan District is one of the areas under the jurisdiction of Jilin City, Jilin Province, which gets its name because it is located in the foothills of Longtan. Located in the northeast of Jilin City, the north bank of Songhua River, Longtan District borders Jiaohe City in the east, Fengman District in the southeast, Changyi District in the south and west, and Shulan City in the north. Longtan District covers an area of 1208.9 square kilometers and cultivated land covers an area of 292.27 square kilometers. In 2010, the resident population was 527532, including more than 20 ethnic groups such as Han and Yao. In 2016, Longtan has jurisdiction over 13 streets, 5 towns and 1 township. In 2016, the GDP of Longtan District reached 39.75 billion yuan, an increase of 7 percent over 2015.