Chongming (Chinese: 崇明岛), formerly romanized as Chungming, is an alluvial island at the mouth of the Yangtze River in East China covering 1,267 square kilometers (489 sq mi) as of 2010.

These were initially about 70 kilometers (43 mi) apart and located south of the larger island of Dongbuzhou (t 東布洲, s 东布洲, p Dōngbùzhōu), which came to form part of the peninsula of Qidong in Jiangsu.

In the first year of Jiangzhong Jingguo (1101), Sansha rose for the third time, stabilizing 50 Chinese miles northwest of Yaoliusha.

These immigrants introduced cotton cultivation, which spread widely prior to China's opening to international trade in the later Qing.

[6] In the 2nd year of Hongwu (1396) under the Ming, the prefecture was downgraded to a county[1] but, shortly afterwards, a major subsidence—sinking the entirety of Dongsha and most of Xisha—provoked a mass emigration back to the mainland.

[1] Over the course of the Ming, numerous shoals arose in succession: Ma'ansha, Chen'ensha, Gaomingsha, Xiaoyinsha, Changsha, Yuanjiasha, Xiangsha, Gaotousha, and around 20 others.

Over the two hundred years from the beginning of Jiajing (1522) under the Ming to the end of Kangxi (1722) under the Qing, these shoals frequently flooded or collapsed back into the river.

During the Second World War, Chongming was administered first by a separate pacification team, then as part of Shanghai's Great Way Government,[7] and finally as a county of the Wang Jingwei regime, a Japanese puppet state in Nanjing.

[9] Dongtan was a proposed ecocity which was planned to open along with the 2010 World Expo in Shanghai but stalled following the 2006 ouster of the Communist Party Chief Chen Liangyu.

The island forms the northernmost part of the municipality of Shanghai, separated by the Yangtze from Baoshan and Pudong New Area, which face each other across the mouth of the Huangpu.

The island of Yonglongsha appeared in the north channel of the Yangtze most recently in 1937 and was stabilized and expanded by workers from Nantong in Jiangsu during the late 1960s.

West Chongming offers Mingzhu Lake Park, Xiling Resort, Xisha Wetland and agritainment at Lugang Village.

Chengqiao's 10-square-kilometer (3.9 sq mi) Chongming Industrial Zone was established in March 1994 and promoted to municipal status in February 1996.

[18] Chongming is also a center of Shanghai's shipbuilding and maritime equipment industries, whose main base is on nearby Changxing.

From northwest to southeast, the towns are Xinhai (新海镇), Lühua (绿华镇), Sanxing (三星镇), Miaozhen (庙镇), Dongping (东平镇), Gangxi (港西镇), Jianshe (建设镇), Chengqiao (城桥镇), Xinhe (新河镇), Shuxin (竖新镇), Gangyan (港沿镇), Buzhen (堡镇镇), Xianghua (向化镇), Zhongxing (中兴镇), and Chenjia (陈家镇).

The Chonghai Bridge under construction will link Xinhai at the west end of the island with Haimen District in Nantong, Jiangsu, while the proposed S7 (Huchong) Expressway would connect Chengqiao directly with Baoshan across the Yangtze.