COLUMBIA RIVER, a stream of the north-west United States and south-west Canada, about 939 m. in length, draining a basin of about 250,000 sq. m., of which 38,395 are in British Columbia; some 105,000 sq. m. belong to the valley of the Snake and 11,700 to that of the Willamette. The source of the river is partly in the Yellowstone country, partly near the Titon peaks, and partly in the pine-clad mountains of British Columbia. Some American geographers regard the head as that of the Clark Fork, but it is most generally taken to be in British Columbia about 80 m. north of the United States line. From this point it runs some 150 m. to the north-west to the “Big Bend,” and then in a great curve southward, enclosing the superb ranges of the Selkirks, crossing the international line near the boundary of Washington and Idaho, where it is joined by the Pend Oreille river, or Clark Fork, already referred to. This latter river rises in the Rocky Mountains west of Helena, Montana, falls with a heavy slope (1323 ft. in 167 m.) to its confluence with the Flathead, flows through Lake Pend Oreille (27 m.) in northern Idaho, and runs in deep canyons (falling 900 ft. in 200 m.) to its junction with the Columbia, which from this point continues almost due south for more than 106 m. Here the Columbia is joined by the Spokane, a large river with heavy fall, and enters the “Great Plain of the Columbia,” an area of some 22,000 sq. m., resembling the “parks” of Colorado, shut in on all sides by mountains: the Moses range to the north, the Bitter Root and Cœur d’Alène on the east, the Blue on the south, and the Cascades on the west. The soil is rich, yielding great harvests of grain, and the mountains rich in minerals as yet only slightly prospected. After breaking into this basin the river turns sharply to the west and skirts the northern mountain barrier for about 105 m. Where it strikes the confines of the Cascades, it is joined by the Okanogan, turns due south in the second Big Bend, and flows about 200 m. to its junction with the Snake near Wallula.
After the confluence of the Snake with the Columbia the greater river turns west toward the Pacific. Throughout its course to this point it may be said that the Columbia has no flood plain; everywhere it is cutting its bed; almost everywhere it is characterized by canyons, although above the Spokane the valley is much broken down and there is considerable timbered and fertile bench land. Below the Spokane the canyon becomes more steep and rugged. From the mouth of the Okanogan to Priests Rapids extends a superb canyon, with precipitous walls of black columnar basalt 1000 to 3000 ft. in height. The finest portion is below the Rock Island Rapids. In this part of its course, along the Cascade range in the Great Plain and at its passage of the range westward, rapids and cascades particularly obstruct the imperfectly opened bed. In the lower Columbia, navigation is first interrupted 160 m. from the mouth at the Cascades, a narrow gorge across the Cascade range 4.5 m. long, where the river falls 24 ft. in 2500; the rapids are evaded by a canal constructed (1878–1896) by the Federal government, and by a portage railway (1890–1891). Fifty-three miles above this are the Dalles, a series of falls, rapids and rock obstructions extending some 12 m. and ending at Celilo, 115 m. below Wallula, with a fall of 20 ft. There are also impediments just below the mouth of the Snake; others in the lower course of this river below Riparia; and almost continuous obstructions in the Columbia above Priests Rapids. The commerce of the Columbia is very important, especially that from Portland, Vancouver, Astoria, and other outlets of the Willamette valley and the lower Columbia. The grain region of the Great Plain, the bottom-land orchards and grain field on the plateaus of the Snake, have not since 1880 been dependent upon the water navigation for freighting, but in their interest costly attempts have been made to open the river below the Snake uninterruptedly to commerce.
The Columbia is one of the greatest salmon streams of the world (see Oregon). The tonnage of deep-sea vessels in and out over the bar at the river’s mouth from 1890–1899 was 9,423,637 tons. From 1872–1899 the United States government expended for improvement of the Snake and Columbia $6,925,649. The mouth of the latter is the only deep-water harbour between San Francisco and Cape Flattery (700 m.), and the only fresh water harbour of the Pacific coast. To facilitate its entrance, which, owing to bars, tides, winds, and the great discharge of the river, has always been difficult, a great jetty has been constructed (1885–1895, later enlarged) to scour the bars. It was about 4.5 miles long, and in 1903 work was begun to make it 2.5 miles longer. The tides are perceptible 150 m. above the mouth (mean tide at Astoria c. 6.2 ft.), the average tidal flow at the mouth being about 1,000,000 cub. ft. per second; while the fresh water outflow is from 90,000 to 300,000 cub. ft. according to the stage of water, and as high as 1,000,000 cub. ft. in time of flood. Improvements were undertaken by the Federal government and a state commission in 1902 in order to secure a 25-ft. channel from Portland to the sea.
In 1792, and possibly also in 1788, the river mouth was entered by Captain Robert Gray (1755–1806) of Boston, Mass., who named the river after his own vessel, “Columbia,” which name has wholly supplanted the earlier name, “Oregon.” In 1804–1805 the river was explored by Meriwether Lewis and William Clark. Upon these discoveries the United States primarily based its claim to the territory now embraced in the states of Oregon and Washington.