Page:Popular Science Monthly Volume 60.djvu/122

114 Population in the United States, and Increase in each Census Period of the Nineteenth Century.

Thus it is quite plain that something has happened in the United States to diminish the rate of increase of population after 1860. Up to that time the growth in each census period from 1800 downwards had ranged between 33 and 36 per cent. Since then the highest rates have been 30 per cent, between 1870 and 1880 and 25 per cent: between 1880 and 1890. There is a suspicion, moreover, that, owing to errors in the census of 1870, which were corrected in 1880, the increase between 1870 and 1880 was not quite so high as stated. There is accordingly a somewhat steep decline from a growth in each ten years prior to 1860, ranging between 33 and 36 per cent., to a growth first of about 25 per cent., and finally of 21 per cent. only. The Civil War of the early sixties naturally occurs to one as the explanation of the break immediately after 1860, but the effects could hardly have continued to the present time, and a more general explanation is suggested.

Other special explanations have occurred to me as partly accounting for the change. One is that, prior to 1860, the United States at different times increased its territory and population partly by purchase and partly by annexation. But I cannot make out that either the purchase of Louisiana early in the century, or the subsequent annexations following the Mexican war, would make a material difference. There is a considerable increase certainly after the Mexican war, but it would be difficult indeed to estimate how much of the population of Texas and New Mexico, which was then added to the Union, had previously swarmed over from the Union, and had thus been from the first economically, if not politically, part of the United States. Another obvious suggestion is that possibly immigration into the United States