The image of the Wild West as a vast expanse populated by solitary young men is quite far from the truth. After the Civil War, the US started to expand its industry and agriculture westward into lands already populated by Native Americans, migrants from Europe and China, and Mexicans that were established there since before the Treaty of Hidalgo.
Railroads brought supplies and people to the West and many towns and estates were founded close to the stations. In their battle against the Native Americans in the West, the American government systematically hunted and killed millions of buffalo, upon which the native populations relied. By 1890, after many conflicts across the frontier, most Native Americans had been moved to relatively small reservations.