life. Railroads, fostered by land grants, sent an increasing tide of immigrants into the Far West. The United States Army fought a series of Indian wars in Minnesota, Dakota, and the Indian Territory.
By 1880 the settled area had been pushed into northern Michigan, Wisconsin, and Minnesota, along Dakota rivers, and in the Black Hills region, and was ascending the rivers of Kansas and Nebraska. The development of mines in Colorado had drawn isolated frontier settlements into that region, and Montana and Idaho were receiving settlers. The frontier was found in these mining camps and the ranches of the Great Plains. The superintendent of the census for 1890 reports, as previously stated, that the settlements of the West lie so scattered over the region that there can no longer be said to be a frontier line.
In these successive frontiers we find natural boundary lines which have served to mark and to affect the characteristics of the frontiers, namely: the "fall line;" the Alleghany Mountains; the