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
The route west was arduous and fraught with many dangers, but the number of deaths on the trail is not known with any precision; there are only wildly varying estimates. Estimating is difficult because of the common practice of burying people in unmarked graves that were intentionally disguised to avoid their being dug up by animals or Indians. Graves were often put in the middle of a trail and then run over by the livestock to make them difficult to find. Disease was the main killer of trail travelers; cholera killed up to 3 percent of all travelers in the epidemic years from 1849 to 1855.