Haimen is a district of Nantong, Jiangsu province, with a population of approximately 1 million. It is located at the opposite side of the Yangtze River to Shanghai and is directly north of Chongming Island except for a small portion that forms Haimen District's Haiyong Town. Haimen is the seat of the Roman Catholic Diocese of Haimen. Haimen is located in the poorer north Jiangsu region and, together with Qidong City, has long had one of the highest rates of liver cancer in China and in the world; over one in ten adults in the rural areas died from liver cancer c.1970, with mortality halving since then with improvements to drinking water and food.