In April 1846, St. Louis, a major trading town west of the Mississippi River, was extremely busy. Gathering here, in addition to those businessmen who regularly go to Santa Fe to do business in late spring every year, there are also many strangers from all over the East Coast who are planning to move to California and Oregon. There are only muddy and potholed grasslands and difficult and dangerous mountains ahead. St. Louis, located at the confluence of the Mississippi River and the Missouri River, is the last large town where white colonists live. The town’s inns were full; the shops were bustling, and artisans worked day and night creating…