According to Maurice S. Sullivan, Smith was "the first white man to cross the future state of Nevada, the first to conquer the High Sierra of California, and the first to explore the entire Pacific Slope from Lower California to the banks of the Columbia River". He was known for his many systematic recorded observations on nature and topography. His expeditions also raised doubts about the existence of the legendary Buenaventura River. Jedediah Smith's explorations were the main basis for accurate Pacific West maps. He and his partners, Jackson and Sublette, produced a map that, in a eulogy for Smith printed in the "Illinois Magazine" for June 1832, the unknown author claimed "This map is now probably the best extant, of the Rocky Mountains, and the country on both sides, from the States to the Pacific." This map has been called "a landmark in mapping of the American West" The original map is lost, its content was overlaid and annotated by George Gibbs on an 1845 base map by John C. Frémont, which is on file at the American Geographical Society Library, at the University of Wisconsin-Milwaukee.