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 Mississippi; the Missouri where its direction approximates north and south; the line of the arid lands, approximately the ninety-ninth meridian; and the Rocky Mountains. The fall line marked the frontier of the seventeenth century; the Alleghanies that of the eighteenth; the Mississippi that of the first quarter of the nineteenth; the Missouri that of the middle of this century (omitting the California movement); and the belt of the Rocky Mountains and the arid tract, the present frontier. Each was won by a series of Indian wars. At the Atlantic frontier one can study the germs of processes repeated at each successive frontier. We have the complex European life sharply precipitated by the wilderness into the simplicity of primitive conditions. The first frontier had to meet its Indian question, its question of the disposition of the public domain, of the means of intercourse with older settlements, of the extension of political organization, of religious and educational activity. And the settlement of these and similar questions for one frontier served as a guide for the next. The American student needs not to go to the "prim little townships of Sleswick" for illustrations of the law of continuity and development. For example, he may study the origin of our land policies in the colonial land policy; he may see how the system grew by adapting the statutes to the customs of the successive frontiers.[10:1] He may see how the mining experience in the lead regions of Wisconsin, Illinois, and Iowa was applied to the mining laws of the Sierras,[10:2] and how our Indian policy has been a series of experimentations on successive frontiers. Each tier of new States has found in the older ones material for its constitutions.[10:3] Each frontier has made similar contributions to American character, as will be discussed farther on.