In the summer of 1885, Lieutenant Henry Tureman Allen of the U.S. Army undertook the first recorded exploration of the Tanana River. In 1883, Lieutenant Frederick Schwatka and his party had entered the Yukon watershed by way of Canada and floated to the mouth of the Yukon. Allen's goal was to find an all-Alaska route to the Yukon River. He and his men ascended the Copper River, crossed into Tanana River drainage, and descended the Tanana to the Yukon and down it to the mouth. During the five-month trip, the Allen party mapped the courses of the Copper, Tanana, and Koyukuk rivers.