Adopted in 1898 in the 1st Report of the Geographic Board of Canada; application of Yukon portion altered and re-passed 2 June 1950 on Canadian Geological Survey map 115A.

Source: BC place name cards, or correspondence to/from BC's Chief Geographer or BC Geographical Names Office

Variously labelled Alseck, Alsekh, Altsek, Altsekh and Alzech. "Alsekh" is the native name, reported by Captain Tebenkov, Imperial Russian Navy, 1825. Had been called "Rivière du Behring" by La Perouse in 1786; identified as "Jones River" by the New York Times 1886 Expedition, after one of their sponsors; identified as "Harrison River" by US Coast & Geodetic Survey 1890, after a US president. The original name, in the form "Alsek", was adopted by Canada and USA in 1891.

Source: BC place name cards, or correspondence to/from BC's Chief Geographer or BC Geographical Names Office

The preferred Southern Tuchone spelling is Ałséxh´, a possessive name meaning "the river belonging to Ałséxh´" (1999 advice from Yukon Native Language Centre)

Source: BC place name cards, or correspondence to/from BC's Chief Geographer or BC Geographical Names Office

" place where people rest " river. (translation from Yukon Geographical Names Program).

Source: included with note

Headwaters in Yukon at 60 38-137 47 on 115 A/12. Flows southwest across BC-Yukon boundary at 60 00-137 49 on 115 A/4. Length in BC = 89 miles (measured on BC map 1H, 1917). Mouth in Alaska.

Source: Canadian Geographical Names Database, Ottawa