COLUMBIA, or OREGON, after the Yukon, the largest river on the western side of America. It rises in the Kootenay District of British Columbia, on the western slope of the Rocky Mountains, near mounts Brown and Hooker, in about lat. 50° N. Its course, which is very irregular, is generally southwest through British Columbia and Washington. It forms the northern boundary of Oregon for about 350 miles and enters the Pacific by an estuary 35 miles long and from 3 to 7 wide. Its estimated length is 1,400 miles, and the area drained by it and its tributaries, of which the largest are Clarke's Fork (with the Mis soula, 700 miles long), and the Snake River (940 miles in length) along which are very remarkable canyons, has been computed to be 298,000 square miles. The river is broken by falls and rapids into separate portions, and formerly a bar across its mouth obstructed nav igation. The construction of ajetty two and one-half miles long has provided a good har bor, but the sit deposit calls for constant dredg ing and other work. Sea-going vessels ascend
the Columbia for 100 miles to the Willamette and from the junction with the latter to Port land (10 miles), while steamboats reached the Cascades (160 miles), where there was a port age of 6 miles which was bridged over by a railway; and beyond this another navigable stretch of 50 miles to the Dalles. In November 1896 the government completed a canal and locks at the Cascades, at an expense of nearly $4,000,000, and thus opened navigation to the Dalles, where a 14-mile railroad passes round the Great Dalles channel to the next section above (185 miles), beyond which there is a final part navigable for 250 miles by steam boats. The Columbia and its branches have 2,132 miles of navigable waters. The extraor dinary abundance of salmon in the river has developed numerous fisheries which have been well exploited. Near the mouth are a number of canneries. Captain Gray of Boston entered the river in 1792, and Lewis and Clark ex plored it in 1805.