Cholera outbreaks and pandemics
That year, cholera was transmitted along the California, Mormon and Oregon Trails as 6,000 to 12,000 are believed to have died on their way to the California Gold Rush, Utah and Oregon in the cholera years of 1849–1855. It is believed more than 150,000 Americans died during the two pandemics between 1832 and 1849.
Oregon Trail
There were several U.S. government-sponsored explorers who explored part of the Oregon Trail and wrote extensively about their explorations. Captain Benjamin Bonneville on his expedition of 1832 to 1834 explored much of the Oregon trail and brought wagons up the Platte, North Platte, Sweetwater route across South Pass to the Green River in Wyoming. He explored most of Idaho and the Oregon Trail to the Columbia. The account of his explorations in the west was published by Washington Irving in 1838. John C. Frémont of the U.S. Army's Corps of Topographical Engineers and his guide Kit Carson led three expeditions from 1842 to 1846 over parts of California and Oregon. His explorations were written up by him and his wife Jessie Benton Frémont and were widely published. The first detailed map of California and Oregon were drawn by Frémont and his topographers and cartographers in about 1848.