River, west-central Russia.
The largest tributary of the Volga River , it rises in Udmurtiya and flows for 1,122 mi (1,805 km) until it enters the Volga below Kazan. Navigation is possible for about 955 mi (1,535 km). It is one of the most important rivers of Russia, historically as the route to the Urals and Siberia and economically as part of the vast Volga system of waterways.