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.
Chongzuo, a prefecture-level city under the jurisdiction of Guangxi Zhuang Autonomous region, is located in the southwest of Guangxi Zhuang Autonomous region, with geographical coordinates between 21 °36` ~ 23 °22` N and 106 °33` ~ 108 °6` E. it is bordered by Nanning City and Fangchenggang City in the east and southeast, Baise City in the north and Vietnam in the west. It is the prefecture-level city with the longest land border in Guangxi, with a total area of 17440 square kilometers. Chongzuo is the most convenient land passage from China to ASEAN, an important node city of China-Vietnam Corridor and Nanning-Singapore Economic Corridor, and one of the cities of Guangxi Beibu Gulf Economic Zone. There are 3 national first-class ports, 4 second-class ports and 13 border exchange points, which is the city with the largest number of border ports in China. The topography of Chongzuo City is slightly higher in the northwest and southwest.