…The importance of the result can hardly be overestimated. It ensured the peaceful and free development of the great West and gave it political organization not as the outcome of wars of hostile States, nor by arbitrary government by distant powers, but by territorial government combined with large local autonomy. These [local] governments in turn were admitted as equal States of the Union. By this peaceful process of colonization a whole continent has been filled with free and orderly commonwealths so quietly, so naturally, that we can only appreciate the profound significance of the process by contrasting it with the spread of European nations through conquest and oppression.
A period of almost constant Indian hostility followed, for the savage lords of the boundless prairies instinctively felt the significance of the entrance of the farmer into their empire. In Minnesota the Sioux took advantage of the Civil War to rise; but the outcome was the destruction of their reservations in that State…. The systematic slaughter of millions of buffalo … put an end to the vast herds of the Great Plains, and destroyed the economic foundation of the Indians. Henceforth they were dependent on the whites for their food supply, and the Great Plains were open to cattle ranchers.