may be made of plateaux and mountain regions. In the census of 1900, this classification was taken up in a brief and supplementary way, and the area, population and density of the several physiographic regions were computed and are placed before the reader. The areas are not exact, for the boundaries had to be determined by the nearest available county lines, but the error can hardly be of disturbing proportions.
It is not here possible to exhibit or discuss the interesting facts brought out by this new departure of the census. It marks, however, a step of progress in understanding the adjustment of our people to their environment. Under the designation of New England Hills are included New England, the Adirondacks and the foothill country east of the Hudson in the state of New York. The density for this region is the highest in the United States, 124.1. How strongly population turns on other factors than soil, thus appears, and the result becomes astonishing when we put down in comparison the present density of the prairie region, viz., 29.2.
Using the new land classification, we may approach again the possible or probable population east of the great plains, or in the well-watered eastern section of the United States. Leaving out the New England Hills, which already exceed the density we are about to propose, and omitting the Appalachian Plateau and the Ozark Hills, it would seem reasonable to expect an average density of 100 for the remaining territory of the east. This is about the density of Europe. The territory for which we propose it includes the coastal plains and lowlands, the Appalachian Valley, the piedmont and lake regions, the Mississippi alluvial region, the interior timbered region and the prairies. One need not apologize for thinking this aggregate physically as good as average Europe. Two of the regions, the Appalachian Valley and the piedmont, already have more than three fourths of the density proposed, and the interior timbered region, so far from being the wilderness implied by its name, has a density of 68.7. Raising the whole to 100, we pass from the present 53,800,000 to 127,600,000. If to this total we add the present population of the New England Hills, the Appalachian Plateau and the Ozark Hills, we bring our total to 145,000,000. If we allow reasonably for the growth of these three regions we place the figure at 150,000,000.
A density of 100, however, seems a low expectation for the prairies, and also for the lake region, which last already has 55.2 persons per square mile. Considering the soil, climate, minerals and transportation facilities of the lake borders, their population must largely increase. Give these two regions the present density of France or of Austria-Hungary, we must add to the total already reached, 40,000,000 for the prairies and 15,000,000 for the lakes, bringing our total east of the great plains to 205,000,000.
Iowa is a typical prairie state and has 55,475 square miles, not counting a few hundred miles of water surface. This state has about
