This map, produced in 1846 in seven sections, was compiled by order of the U.S. Senate from the field notes and journal of Captain John C. Frémont (1813−90) and associated sketches and notes of his assistant, Charles Preuss (1803−54). It traces the route to the Pacific paralleling the large river systems traversing the North American continent. Frémont was an experienced frontiersman who led four expeditions into the western regions of the United States. Popularly known in his day as “The Pathfinder,” Frémont worked with the frontiersman Kit Carson and made large contributions to early knowledge about the geography of the American West. Each section of the map shows in great detail the initial route that Frémont took on his second expedition, in 1843−44, along the Kansas, Platte, Snake, and Walla Walla Rivers and parts of the Oregon Trail. The map includes temperature readings, altitude, and weather patterns for each day of the journey, as well as extensive notes describing the terrain, flora and fauna, and the Native American tribes encountered. The scale is 10 miles to the inch (16.09 kilometers to 2.54 centimeters). As one of the most famous explorers of the West, Frémont became military governor of California in 1847, one of the first senators from California in 1850, and the first Republican candidate for president of the United States in 1856. In 1853 he published The Exploring Expedition to the Rocky Mountains, Oregon and California: To Which is Added a Description of the Physical Geography of California: With Recent Notices of the Gold Region from the Latest and Most Authentic Sources.