city and port, southwestern Liaoning sheng (province), northeastern China. It is situated just inland from Liaodong Bay (an arm of the Bo Hai 【Gulf of Chihli】) near the mouth of the Daliao River, some 11 miles (18 km) from the mouth of the Liao River.

Yingkou began to develop as a river port in the second quarter of the 19th century, later replacing Niuzhuang and Tianzhuangtai farther upstream. At first the new port was called Mogouying (“Mogou Encampment”) for the garrison of coastal defense troops that was quartered there; the name was later changed to Yingzikou, or Yingkou. Under the Treaty of Tianjin (1858), Niuzhuang was opened to foreign trade, but silt in the lower Liao River (connected upstream with the Hun River) made it unusable, and instead Yingkou was used as the port from 1861 onward. Somewhat confusingly, Europeans referred to the port as Newchwang (Niuzhuang), the name of the original treaty port.

In the late 19th century Yingkou grew into a major port and was the principal outlet for goods from Manchuria (Northeast China). It was essentially a cargo transshipment point between the small junks that used the Liao River and seagoing ships. It was not, however, a very satisfactory port, since it was constantly silting up and was also icebound for three months of the year. Its importance largely vanished in the first decade of the 20th century because of the construction of railways in Manchuria, which diverted most of Yingkou's former trade to Dalian (Dairen). With the construction of its own rail link with the line from Dalian to Shenyang (Mukden; now the provincial capital), Yingkou later regained something of its old importance, exporting great quantities of soybeans and manufacturing bean cake and vegetable oil. The city had a large foreign (mainly Japanese) community.

Contemporary Yingkou has developed into an important secondary industrial city, mostly engaged in light industry. There are cotton mills, knitting factories, oil-extraction plants, canneries, food-processing plants, and paper mills. The area is also a fishing base and has some large evaporating pans for producing sea salt. An engineering sector, specializing in the manufacture of machine tools, and a large-scale oil refinery also have been established. In 1985 Yingkou was designated one of China's “open” cities as part of the country's liberalized economic policy of inviting foreign trade and investment, and factories manufacturing electric appliances subsequently were established. In addition to its rail connections, an expressway connects the city with Dalian and Shenyang. A new seaport opened at Bayuquan in 1986, some 25 miles (40 km) south of the city centre. Pop. (2002 est.) city, 528,961; (2007 est.) urban agglom., 795,000.