Shanghai is one of the four direct-controlled municipalities of China and the most populous city proper in the world, with a population of more than 24 million as of 2017. It is a global financial centre and transport hub, with the world's busiest container port. Located in the Yangtze River Delta, it sits on the south edge of the estuary of the Yangtze in the middle portion of the East China coast. The municipality borders the provinces of Jiangsu and Zhejiang to the north, south and west, and is bounded to the east by the East China Sea.
As a major administrative, shipping and trading city, Shanghai grew in importance in the 19th century due to trade and recognition of its favourable port location and economic potential. The city was one of five treaty ports forced open to foreign trade following the British victory over China in the First Opium War. The subsequent 1842 Treaty of Nanking and 1844 Treaty of Whampoa allowed the establishment of the Shanghai International Settlement and the French Concession. The city then flourished as a centre of commerce between China and other parts of the world, and became the primary financial hub of the Asia-Pacific region in the 1930s.