the Amur river is about 1800 miles (2900 km) long.
Amur River, a river in northeast Asia. The Chinese call it Heilong Jiang, meaning “Black Dragon River.” Measured from the junction of its main headstreams, the Shilka and Argun rivers, the Amur is about 1,800 miles (2,900 km) long. With the Shilka and Onon, the system measures about 2,700 miles (4,350 km) in length. More than 1,000 miles (1,600 km) of its course forms the boundary between Russia and China.