East of the Cascade Mountains the Columbia and Spokane rivers mark the boundary between the Okanogan Highlands to the northward and the Columbia plateau to the southward; The Okanogan Highlands, an outlier of the Rocky Mountains extending westward from the Coeur d'Alene Mountains in Idaho, reach heights of 5000 to 6000 ft.
The Spokane, Portland & Seattle railway connects the three cities named by way of the Columbia Valley; and the Spokane & Inland Empire sends a line eastward into Idaho to the Coeur d'Alene country and another through the south-eastern part of the state into Nevada.
The richest deposits of silver are those of Wood river and of the Coeur d'Alene district in Shoshone county (opened up in 1886); the county's product in 1906 was valued at $5,322,706, an increase of $917,743 over the preceding year; in 1907 it was $4,780,093, according to state reports.
Brick-making was of little more than local importance in 1906, the largest kilns being at Boise, Sand Point and Coeur d'Alene City.
Occasional labour troubles have been very severe in the Coeur d'Alene region, where the attempt in 1892 of the Mine Owners' Association to discriminate in wages between miners and surfacemen brought on a union strike.
