YUKON, yoolcon, North America, a large river, mainly in the United States Territory of Alaska, which rises as the Lewes in British Columbia, about lat. 59° and after a tortuous northwest by south, and northwest course of 2,300 miles, flows into Bering Sea, on the southern shore of Norton Sound, through a delta from 80 to 90 miles wide. The northernmost channel of the delta, the Aphoon Mouth, is the only one navigable. It has a drainage area of 330,000 square miles. The main stream of the Yukon is formed at Fort Selkirk in 63°, by the junction of the Lewes and the Pelly, the former being con stituted by the junction of the Big Salmon and Teslin flowing from Teslin Lake and draining a group of small lakes in the region around Mounts Landsdowne and Lorne. From Fort Selkirk, the Yukon flows northwest with many windings, passing through the Klondike gold field, receiving from the right the Stewart River, and at Dawson the Klondike, and from the left the White River, Sixty-Mile Creek and Forty Mile Creek. It enters Alaska in about 65° N. and continues its northwestern course until Arctic Circle is reached, when at the abandoned Fort Yukon it is joined on the right by the Porcupine River, bends suddenly, almost at right angles, and thenceforward has a general south western trend to its mouth.
The chief Alaskan tributaries of the Yukon are the Kozukuk on the right bank, and the Birch and Tanana on the left bank. Its whole
course of 1,260 miles through Alaska is navi gable by stern-wheel steamers, and beyond to Dawson in Canada; since the discovery of gold throughout the region in 1897 a regular summer service is maintained; the first impracticable obstruction to navigation is at the Grand Canon, 1,866 miles from the mouth. In its lower course the Yukon is a broad, muddy stream flowing mostly through a marshy plain and for nearly nine months of the year, from October to June, frozen over; its upper course is through the grand scenery of narrow moun tain valleys and rocky gorges. The Yukon is the largest American river flowing into the Pacific; it is the 17th river of the world as to length, the seventh of the Western hemi sphere, the fifth of the North American con tinent and the third in the United States. This last assertion is based on its whole length of 2,300 miles, however, but taking only that por tion which is in the United States, or Alaska, 1,260; it is the fifth river of our country, the Mississippi, Missouri, Arkansas and Ohio avers being longer. There are but four rivers in the world with a greater capacity, the Amazon, the Mississippi, the Missouri and the Saint Law rence.