people started to move west of the mississippi river and the rocky mountains at this time. the first people who moved west were people who caught and sold animal skins such as john colter and jim bridger. by the 1840s, many people were moving to oregon by wagon, and even more people went west after the california gold rush of 1849. many new states were added to the first thirteen, mostly in the midwest and south before the civil war and in the west after the civil war. during this period, native americans lost much of their land. they had lost military battles to the americans at tippecanoe and in the seminole war. in the 1830s, indians were being pushed out of the midwest and south by events such as the trail of tears and the black hawk war. by the 1840s, most native americans had been moved west of the mississippi river.