John Charles Frémont & Charles Preuss, Topographical Map of the Road from Missouri to Oregon (1846)

John Charles Frémont , who became known as "the Great Pathfinder" because of his westward expeditions, was a member of the Army Corps of Topographical Engineers, and son-in-law of Senator Thomas Hart Benton, a driving force behind the "Manifest Destiny" movement.  This seven-sheet traverse map of the "Oregon Trail" was a cartographic collaboration between Frémont and Charles Preuss, a surveyor of Prussian origin, who went together on several expeditions between the Rockies and Pacific Ocean. Each sheet covered about 250 miles and was drawn at the scale of 10 miles to the inch, providing a high level of detail for emigrants to the west. Information on the map included weather patterns, vegetation and soils, animal life, water sources, and the presences of Native Americans.  According to James R. Akerman and Robert W. Karrow, Jr., the map was critical in shaping people's perceptions of the west prior to the California gold rush.