The islands of Shanghai are those under the jurisdiction of the Shanghai municipal government. They comprise three large inhabited islands and a shifting number of smaller, uninhabited ones. Most are alluvial islands in the Yangtze River Delta in China, although a number of islands in Hangzhou Bay off Jinshan District are also administered by Shanghai. The alluvial islands are relatively young and their number varies over time. In 2006, the city's 19 uninhabited islands covered 226.27 square kilometers (87.36 sq mi), with a total coastline length of 309 kilometers (192 mi).
The Yangshan area of the Port of Shanghai is also located on two islands, Greater and Lesser Yangshan in Hangzhou Bay, but these are administered as part of Zhejiang's Shengsi County.
All three inhabited islands of Shanghai are alluvial islands in the Yangtze estuary between the Municipality of Shanghai and Jiangsu Province. They are administered as Chongming County, with its seat at Chengqiao on Chongming Island. The county was added to Shanghai from Jiangsu in 1958 and remains mostly rural: In 2008, its registered population of 693 000 included 450 300 farmers.
Chongming Island (1,267 km2 or 489 sq mi) is now the second-largest island of mainland China (after Hainan). The natural expansion of the island has been greatly accelerated by reclamation projects, which doubled its size between 1950 and 2010. This growth caused it to absorb the former island of Yonglongsha, creating a long pene-exclave of Jiangsu on its northern shore administered as the townships of Haiyong and Qilong. The island was connected to Changxing by the Yangtze Bridge in 2009 and to Qidong in Jiangsu by the Chongqi Bridge in 2011. The Chonghai Bridge, to Haimen in Jiangsu, remains under construction and plans for Shanghai's S7 (Huchong) Expressway call for the creation of a bridge directly from Baoshan District to Chengqiao.