the spring of 1827, Daniel Potts, a fur trader in the employ of Smith, encountered the Sevier River downstream from the point Smith had the previous summer. He continued to follow the river downstream to the Sevier Lake, which he confirmed was a saline lake, but did not try to circumvent it to find an outlet. He instead followed the entire course of the river upstream to its head. The Buenaventura River's existence or non-existence was a matter of controversy until 1843, when John Charles Frémont, with Thomas Fitzpatrick and Kit Carson as scouts, led a perilous expedition from the Columbia River to Sacramento, California via the Sierra Nevada. By that time the fact that the Buenaventura River did not flow from the headwaters of the Colorado/Green River was well established among the trappers and guides, but maps continued to show it and other rivers flowing from the region of Great Salt Lake to the sea. On January 27, 1844 at Walker River, he briefly believed himself to have found the mythical river, but it was the result of a faulty measurement. Two days later he discovered his mistake and definitively proved that the Buenaventura did not exist. Upon later finding the Salinas River flowed into the Pacific at about the same point the maps depicted the mouth of the Buenaventura, Frémont concluded that it was the source of the legend and applied the name "Rio San Buenaventura" to it. After Frémont established that no rivers flowed across the Great Basin region to the Pacific, President Polk was reluctant to accept his conclusion. However, after the premise was accepted that no east to west waterway flowed across the interior of the western United States, Frémont and his father-in-law and political sponsor, Senator Thomas Hart Benton, directed their ambitions to a transcontinental railway, which was completed in 1869, after the Mexican–American War of 1846–48 and the American Civil War. Notes References Further reading C. Gregory Crampton, The San Buenaventura − Mythical River of the West, in: Pacific Historical Review, Vol. 25, 2 (1956 May), p. 163-171 American folklore American frontier The Californias Geography of the Western United States Green River (Colorado River tributary) History of geography History of the American West New Spain Western United States in fiction