Important early map of Eastern Oregon, bounded by the Willamette, Columbia, and Snake Rivers.

Major Enoch Steen, commander of the U.S. Dragoons, was sent to the area in 1860 to determine the feasibility of routes from the Willamette Valley to southeastern Oregon. However, Steen's historical fame rests on his pursuit, during the expedition, of Paiute (Snake) Indians up the Donner and Blitzen River and into the rough Wildhorse Canyon. According to Wheat, "this was a decisive campaign; the Snakes were defeated and their movements rigorously curtailed."

Steen's report to the Senate of his explorations in Oregon included this highly detailed map by Joseph Dixon. The map depicts the area from Fort Boise on the Snake River, west to Fort Vancouver on the Columbia River. It details the routes of Steen and several scouts against the Snake Indians, as well as showing the Oregon Trail (Emigrant Road), the proposed route to Eugene City, Indian trails, camps, battlegrounds, forts, astronomical stations, topography, and rivers, and it notes several large unexplored regions of the Blue Mountains.

Originally bound into Steen's Topographical Memoir of the Command Against the Snake Indians, under Major E. Steen, United States Dragoons, in the Summer of 1860.