trends E 15 mi. to its terminus at Allen River, 1 mi. W of Copper River and 40 mi. N of Katallla; Chugach Mts.
named by Lawrence Martin for Lieutenant Henry Tureman Allen, USA, 1859-1930, who did extensive exploration in central Alaska. Leaving Nuchek on March 20, 1885 Allen ascended the Copper River, crossed to and descended the Tanana River to its mouth. From there he traveled north to the Koyukuk, ascended it some distance, then descended to its mouth and arrived at St. Michael on August 29. travelled approximately 1,500 miles of wilderness and his maps remained for a dozen years the only source of topographical information on the regions he investigated.