The Silver Valley is a region in the northwest United States, in the Coeur d'Alene Mountains in northern Idaho. It is noted for its mining heritage, dating back to the 1880s. Silver Valley is a narrow valley about 40 miles in length, east of the city of Coeur d'Alene. The South Fork of the Coeur d'Alene River flows through the valley and Interstate 90 traverses th…The Silver Valley is a region in the northwest United States, in the Coeur d'Alene Mountains in northern Idaho. It is noted for its mining heritage, dating back to the 1880s. Silver Valley is a narrow valley about 40 miles in length, east of the city of Coeur d'Alene. The South Fork of the Coeur d'Alene River flows through the valley and Interstate 90 traverses the valley between Fourth of July Pass to the west and Lookout Pass on the Montana border.