Copper, river, c.300 mi (480 km) long, rising in the Wrangell Mts., SE Alaska, and flowing S through the Chugach Mts. to the Gulf of Alaska. Copper deposits near the upper river, long mined by natives, attracted the attention of Russians and later Americans, but exploration was difficult because of the river's currents and the glaciers near its mouth. The great Kennecott mine (discovered 1898; abandoned 1938) was made reachable by the building of the Copper River and Northwestern RR from Cordova, which followed the river along part of its lower valley. Today the Copper is noted for its salmon.