How did western expansion impact slavery and Native Americans?

The relationship between slavery and western expansion was a complex one. In more than one way, slavery (or, more precisely, the desire to cultivate cotton using enslaved people) provided an impetus for western expansion. This was especially true in what historians call the "old" Southwest, a region that extended from western Georgia to eastern Texas. This region, known as the "Black Belt" due to its dark, rich soils, was ideal for growing cotton, and thousands of people flocked to the region, bringing slaves with them, in an effort to get rich off the skyrocketing demand for cotton. This wave of western migration lasted from the 1820s to the 1840s and was accompanied by the growth of an internal slave trade in which at least one million African Americans were separated from their families and sold from places like Virginia, Maryland, and North Carolina to the Deep South. Some Americans even hoped that westward expansion into the regions gained in the Louisiana Purchase and the Mexican Cession might be an avenue for the eventual end of slavery in the east, as planters sold their slaves westward. But in a sense, it was westward expansion that brought slavery to an end in the United States. Because Northerners were opposed to the expansion of slavery and Southerners were uncompromising in their demands that slavery be permitted in the western territories and new states, the issue provoked one crisis after another, which eventually ended in disunion and civil war.
As for Native peoples, westward expansion was an unmitigated catastrophe. In some cases, it led to the total destruction of Native peoples. From the old Southwest, where tribes like the Cherokee and Creek were removed to make room for cotton plantations and mines, to the Great Plains, were the Sioux, Cheyenne, and others were defeated by the US Army in the era following the Civil War, Native peoples were consistently pushed aside by the US government. Many were shunted onto reservations, while others were simply wiped out and dispersed. Even well-meaning Americans saw them as essentially primitive peoples who needed to accept "civilization" as offered by the American government. In short, westward expansion came at the expense of Native Americans.
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