A large folding map published in 1860 in the reports 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.
References: Wheat (TM) 867.
Condition: A
Folding as issued, with a two small paper repairs, still very good.