The most famous of the overland emigrant routes to the Pacific, the Oregon Trail extended over 2,000 miles from Independence, Missouri to the mouth of the Columbia River. Mountain men blazed the Trail in the 1830s but it was not until the 1840s, after returning trappers, traders, surveyors and missionaries had kindled Oregon fever, that the first wagon trains successfully traversed the route. Consisting of canvas-topped “prairie schooners” drawn by horses or oxen, the wagon trains adopted a semi-military organization with elected leaders to enforce discipline and maximize protection. Thus at night, to protect against the danger of Indian attack (which was actually rate), and to prevent animals from straying, the wagons would be drawn up in a tight circular stockade or corral, guarded by sentinels. In 1843, approximately 900 emigrants traveled the Oregon Trail. Their numbers swelled in the years thereafter: an estimated 1,500 in 1844; 2,500 in 1845; and 4,000 in 1847. After the discovery of gold in California in 1848, more than 25,000 took to the Oregon Trail, most branching off at South Pass for California. In 1850, approximately 50,000 traveled the Oregon and its subsidiary trails to California; 60,000 during the peak year of 1852. The Oregon Trail remained a popular overland route until the 1870s when it was superceded by the railroads.