4to (222 x 140 mm). 22 plates, 5 maps including the large folding map by Charles Preuss in separate volume, numerous in-text illustrations (offsetting, spotting throughout, large map linen-backed with some minor separations along folds). 19th century half calf (rubbing, minor soiling); map volume in full 19th century cloth (soiling, minor ink stains on rear).

FIRST SENATE ISSUE. Initially hired to assist French explorer Joseph Nicollet in his explorations of lands between the Mississippi and Missouri rivers, John C. Fremont was chosen to succeed Nicollet when he became too ill to continue further explorations. This expedition's aim was to explore and map the territory for future acquisition by the United States. Over the course of two years and two expeditions Fremont made it through Colorado and the Rocky Mountains to the west coast, accumulating invaluable scientific data and drafting maps of the region, with that made by Charles Preuss considered to be so important as to make 1845 “one of the towering years in the story of Western cartography” (Wheat II:194).  The report was one of the most studied works prior to the gold rush, and the text and maps had a powerful effect on the routes chosen by emigrants to the west. Field 565; Graff, 1436; Howes, F370; Rosenbach. 32:146; Sabin 25845. Soliday I:861; Streeter 3131; Wagner-Camp 115:1. Wheat 497.