land, as well as the most of New York, Pennsylvania, and New Jersey, show the results of commerce and manufactures, where they are firmly established and constitute the leading occupations of the people, which has to a large extent been withdrawn from the country and been grouped in the suburbs of cities and large towns; so the population, which twenty or thirty or perhaps forty years ago did not increase in such localities, is, under the activity stimulated by profitable occupations, increasing rapidly; but in the central parts of Maine, New Hampshire, Vermont, and New York, where the transition from agriculture to commercial and manufacturing industries is still developing, population does not gain with very great strides. The changes from agriculture to commercial and manufacturing pursuits are indicative always of a transition from a permanent to an actively increasing density of population. This is evident in the upper Mississippi Valley and in Virginia, where the transition is becoming apparent. The areas known as the plains of the Cordilleran region are being peopled rapidly. This is particularly true in the northern portions. Cheap lands and easy tillage of the virgin soil are making the competition of Eastern agriculturists unprofitable, and so the farming population of the far Eastern States is recruiting the territory embracing the rich lands of the West. In Nevada we witness the peculiar spectacle of a loss of population resulting from the low condition of the mining interests. These facts as to increase and decrease give an indication of the ever-changing features relating to the density of population in great areas.
Taking the whole country, the progress of growth has been along the thirty-ninth parallel of latitude. The center of population, meaning thereby the center of gravity of the population of the country, each individual being assumed to have the same weight, was, in 1790, twenty-three miles east of Baltimore, Md, In 1890 it was twenty miles east of Columbus, Ind., five hundred and five miles west of the point at which it was located one hundred years ago. The variation of the center from latitude 39°, north or south, has been very slight, the extreme having been less than nineteen minutes, while the movement in longitude has been nearly 912°, On the basis of a uniform movement on the thirty-ninth parallel of latitude, the westward march for the first decade after the census of 1790 was forty-one miles; for the second, thirty-six miles; for the third, fifty miles; for the fourth, thirty-nine miles; for the fifth, fifty-five miles; for the sixth, fifty-five miles; for the seventh, eighty-one miles; for the eighth, forty-two miles; for the ninth, fifty-eight miles; and for the tenth, forty-eight miles, or an average movement each decade of fifty-five and a half miles. The position of the center of population at each census is accurately shown by the following table and the map which accompanies it:
