Shenzhen is a major sub-provincial city and one of the special economic zones of China. The city is located on the east bank of the Pearl River estuary on the central coast of southern province of Guangdong, bordering Hong Kong to the south, Dongguan to the north, and Huizhou to the northeast. With a population of 17.56 million as of 2020, Shenzhen is the fourth most populous city proper in China. Shenzhen is a global center in technology, research, manufacturing, finance, and transportation, and the Port of Shenzhen is the world's fourth busiest container port.
Shenzhen roughly follows the administrative boundaries of Bao'an County, which was established since imperial times. The southern portion of Bao'an County was seized by the British after the Opium Wars and became Hong Kong, while the village of Shenzhen was situated on the border. Due to the completion of a train station that was the last stop on the Mainland Chinese section of the railway between Guangzhou and Kowloon, Shenzhen's economy grew and became a market town and later a city by 1979, absorbing Bao'an County for the next decade.