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.
Tongguan County, which belongs to Weinan City, Shaanxi Province, is located at the eastern end of Guanzhong Plain in Shaanxi Province. It is bordered by Lingbao City, Henan Province in the east, Huayin City in the west, Luonan County in the south, Dali County in the northwest, and Ruicheng County in Shanxi Province across the Yellow River in the north. It is between longitude 110o 090032 "- 110o 25027" east and latitude 34o 230033 "- 34o 390001" north, with a total area of 526 square kilometers. In 2018, Tongguan County had a resident population of 154200, with a regional gross domestic product (GDP) of 4.035 billion yuan, of which the added value of the primary industry was 484 million yuan, the secondary industry was 1.446 billion yuan, the tertiary industry was 2.104 billion yuan, and the primary, secondary and tertiary industries accounted for 12.0% and 35.8% of the GDP, respectively.