Haiphong, city and province-level municipality, northeastern Vietnam. It lies on the northeastern edge of the Red River delta, beside a distributary of the Thai Binh River, 10 miles (16 km) from the Gulf of Tonkin. It is the outport of the capital, Hanoi, 37 miles (60 km) west, and is the country’s third largest city. Haiphong became a seaport in 1874, and through the French colonial period it developed commercially as a port and as the southeastern terminus of the railway coming through Kunming (in southwestern China), Lao Cai, and Hanoi. It became a leading industrial centre powered by coal from the mines across the Gulf of Tonkin at Quang Ninh. After 1954 many new industrial plants were built in the city with aid given by Soviet-bloc countries and by China. Haiphong sustained heavy damage from U.S. bombing raids in the early 1970s but was subsequently rebuilt. Pop. (2009) 769,739.