One of the most popular passes through the Sierras along the Emigrant Trail was Carson Pass, discovered by Kit Carson, a guide to the Fremont Party. Led by John C. Fremont of the United States Army Topographical Corps, the Fremont Party was assigned to survey the Northwest. In May 1843, the party set off from St. Louis and arrived in Fort Hall, Idaho, in September. By November they had reached Fort Vancouver, Washington. Instead of returning east as planned, Fremont led the party south through the Cascade Mountains of Oregon and into the Great Basin of Nevada. In February 1844, he turned west to attempt one of the most significant crossings of the Sierra Nevada into California, and using the pass scouted by Carson, the expedition made the dangerous journey through the Sierras and arrived safely at Sutter’s Fort in Sacramento in March.