With its vast distances the West was peculiarly dependent on river transportation — at least until the coming of the railroads. Since the early 19th century, fur traders had floated their pelts down the natural highway of the Missouri and its tributaries to make St. Louis the great fur center of the nation. At the same time a hardy breed of rivermen poled and steered heavily-laden flatboats down the Mississippi to New Orleans, the early West’s great outlet. But such river traffic was largely one-way, and only when steamboats made it possible to travel upstream was western travel revolutionized. The two decades before the Civil War witnessed tremendous growth in steam navigation on the upper Mississippi, the Missouri, the Arkansas and the Red River of Texas. Overlanders to California and Oregon took steamboats up the Mississippi to St. Louis, then continued up the Missouri (the “Big Muddy”) to jumping off places like Independence. By 1860 steamboats had penetrated 2,200 miles up the Missouri’s winding course as far as Fort Benton in Montana, fostering a river trade that lasted until the 1880s when it lost out to the railroads.

At the beginning of the 18th century, most of the territory north of Mexico that today comprises the American Southwest was, like California, part of the Spanish empire. With the winning of Mexican independence from Spain in 1821, the Spanish laws excluding foreign merchants from the province of New Mexico were swept away and Americans were free to enter the Santa Fe trade. The following year Missourian William Becknell pioneered the Santa Fe trail by taking a pack train of goods the 900 miles from Independence, Missouri to Santa Fe and Taos, and disposing of them at a handsome profit. His success encouraged imitators and when wagons replaced horses and pack mules in 1825, the volume of trade expanded rapidly. Each year until 1844, when Mexico closed Santa Fe to Americans, traders from Missouri arrived to exchange cloth, furniture, china, cutlery, tobacco and spices for silver, blankets, mules, horses and furs. but business was conducted at a price. Under the Mexican system of local government, authority was concentrated in the alcalde, an official possessing sweeping powers all too often used for personal enrichment. Traders refusing to offer bribes or pay arbitrary taxes and fees could find themselves imprisoned and their goods confiscated.