Snare River (also called Lewis fork or river, Saptin river, and Shoshone river), a tributary of the Columbia, rising in the Rocky mountains in N. W. Wyoming, near the sources of the Yellowstone and Madison rivers, at an elevation of about 8,000 ft. above the sea, about lat. 44° N, lon. 110° 30' W. It flows N. W. to the junction of Lewis fork, the outlet of Shoshone and Lewis lakes; then S., expanding in its course into Jackson lake, and again N. W. to the junction of Henry's fork (a total course of nearly 200 m.) in Idaho, about lat. 43° 15', lon. 112°. Henry's fork rises in Henry lake (6,443 ft. above the sea, about lat. 44° 30', lon. 111° 30') in E. Idaho, on the border of Montana, near the head waters of Jefferson river, and has a S. course. From the junction the Snake describes a curve of more than 350 m. through S. Idaho, flowing S. W. and then N. W., and strikes the Oregon border in about lat. 44° 40'; it then flows N. about 200 m., separating Idaho from Oregon and Washington territory, when in about lat. 46° 30' it turns W. into Washington, and after a further course of about 150 m. falls into the Columbia about 20 m. above the Oregon boundary, about lat. 4C° 15', lon. 119°. Its total length is upward of 900 m.

Steamers ascend to Lewiston on the Idaho border; navigation is then impeded for more than 100 m. by shallows and rapids, above which the river is again navigable for 150 or 200 m. In its course through S. Idaho, the Snake flows through a vast canon, varying in depth from 100 to 1,000 ft.; many of its tributaries sink, and, passing under the strata of lava, fall from the sides of the canon into the main stream; and here occur the American, Shoshone, and Salmon falls, for an account of which see Idaho, vol. ix., p. 167. Its chief tributaries on the right bank are the Malade from the north; the Boise, Payette, Weiser, Salmon, and Clearwater (which enters at the point where the Snake leaves the Idaho boundary) from the east; and the Palouse (in Washington) from the north. On the left bank it receives among others the Blackfoot, Port Neuf, Bannack, Raft, Goose, Salmon, and Bruneau, in Idaho; the Owyhee, Malheur, Burnt, and Powder, in Oregon; and the Grande Ronde, just within Washington territory.