The only large port of central China not cut off from the interior by mountains, it is the natural seaward outlet of, and the gateway to, the Chang basin, one of China's richest regions. It handles much of the country's foreign shipping and a large coastal trade. Great sums are expended to keep open its continually silting harbor. A submarine base is in the harbor. A new deepwater port, Yangshan, located on islands 17 mi (27.5 km) SE of Shanghai in the South China Sea, opened in 2005; the port is connected to the mainland by the 20.2-mi (32.5-km) Donghai Bridge. Although water transport is of prime importance, highways radiate outward, and there are rail connections with Nanjing and Hangzhou, with links through those cities to the N and S China networks. A new international airport opened in Pudong (East Shanghai) in 1999.
Despite a lack of fuel and raw materials, Shanghai is China's leading industrial city, with large steelworks; textile mills; shipbuilding yards; oil-refining, gas-extracting, and diamond-processing operations; and plants making light and heavy machinery, electrical, electronic, and computer equipment, machine tools, turbines, chemicals, pharmaceuticals, aircraft, tractors, motor vehicles, plastics, and consumer goods. The city also is a major financial and publishing center and a regional headquarters for many multinational companies, and contains a free-trade zone (est. 2013). Shanghai includes much of the surrounding rural area (over 2,000 sq mi/5,000 sq km); there farms produce the food crops that support the city's population.
In the 1970s and 80s, Shanghai's industrial base was shifted to include more light industries in order to reduce pollution. There was much rebuilding and expansion; new factories emerged around the outskirts of the city, and the northwest section was developed as an industrial district. Development in the 1990s concentrated on Pudong, an area formerly dominated by farms and marshland that was designated a special economic development zone. A project to divert much-needed water for the city from the Chang River into the Huangpu was completed in 1996. The 1990s also brought new bridges and tunnels and a subway system, now the world's longest.