The history of the United States, according to newer views which have largely supplanted, or progressed beyond, those of the New England school of great historians, is the history of the march of a civilization, chiefly English, across the vast North American continent, within the short period of three hundred years. It is the story of the transformation of a wide-stretching wilderness--of an ever-advancing frontier--into great cities, diversified industries, varying social interests, and an intensely complex life. Wave upon wave of races of mankind has flowed over the developing and enlarging West, and each has left its impress on that area. Across the trail of the Indian and the trapper, the highway of the pioneer on his westward journey, have spread the tilled fields of the farmer, or along it has run the railroad. The farm has become a town-site and then a manufacturing city; the trading post at St. Paul and the village by the Falls of St. Anthony have expanded into the Twin Cities of the Northwest; the marshy prairie by the side of Lake Michigan, where the Indians fought around old Fort Dearborn, has come to be one of the world's mighty centers of urban population--and all this transformation within the memory of men now living. The progress of this rapid, titanic evolution of an empire was greatly accelerated by the desires, the strength, and the energy of multitudes of immigrants from Europe; and in at least six great commonwealths of the Northwest the Swedes, Norwegians, and Danes have been among the chief contributors to State-building. During the eighty years ending in June, 1906, among the 24,000,000 immigrants who came to the United States, the Scandinavians numbered more than 1,700,000. Whether viewed as emigrations on the eastern shores of the Atlantic, or as immigrations on the western shores, these modern _Völkerwanderungen_ constitute one of the wonders of the social world, in comparison with which most of the other migrations in history are numerically insignificant. The Israelites marching out of Egypt were but a mass of released bond-men; the invasions of the Goths, Vandals, and Huns were conquering expeditions, full of boisterous, thoughtless, unforecasting energy. Even the immigration from Europe to America in the whole of the seventeenth century scarcely equalled in number the columns which moved westward in any one year from 1880 to 1890. In this flux of humanity, mobile almost to fluidity, various in promise of utility, shifting in proportions of the good and bad, of pauper, refugee, and fanatic, or "bird of passage", sweatshop man, and home-builder, there has been such an interplay of subtle and vast forces that no just and final appreciation can as yet be reached. But some sort of tentative conclusions may be arrived at by intensive study of each immigrant group, following it through years and generations, searching for its ramifications in the body politic and social.