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.
Huaiji County, which belongs to Zhaoqing City, Guangdong Province, is located in the northwest of Guangdong Province, the north of Zhaoqing City and the upper reaches of Suijiang River, a tributary of Beijiang River. It is located in the uplift belt of western Guangdong, with basin areas in the west, low hills and high hills in the middle and south, with a subtropical climate, long summer and short winter, abundant rainfall, and an annual average temperature of 21.1℃. With a total area of 3554.07 square kilometers, it is the largest county in Zhaoqing County. As of 2017, Huaiji County has jurisdiction over 18 towns and one nationality township, with a registered population of 1.1 million and a resident population of 848400. Huaiji County was established in Yintun Township, Sihui County, Nanhai County in the 13th year of Song Yuanjia of the Southern Dynasty (436 years). The Song Dynasty formed the basic realm of today's Huaiji County. The Yuan Dynasty was transferred to Hezhou, Huguangzhong Book Co., Ltd. The Ming Dynasty was transferred to Wuzhou Prefecture in Guangxi. It was assigned to Guangdong Province in March 1952 and Zhao in 1988.