Highly detailed map of the region between the Upper Missouri and the area around Fort Benton to the Columbia River, primarily covering Montana.
The map shows the graphic depiction of the Pacific Railroad Surveys as they surveyed for a northern route (47th and 49th Parallels) on an expedition led by Isaac Stevens, Governor of Washington Territory. Most of the map covers Montana, with extraordinary detail and excellent relief, naming rivers, numerous routes with dates, and interesting topographical commentary.
The map shows a number of important explorer routes and wagon roads, including Mullan, Stevens, Lambert, Tinkham, Stanley and many others. Extends north to Ft. Colville.