Page:Popular Science Monthly Volume 81.djvu/211

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205
THE PROGRESS OF SCIENCE

PSM V81 D211 Percent increase of us population between 1900 to 1910.png

Per cent, of increase in total Population by States, 1900-1910.

 

states, followed in order by New Jersey, Connecticut, New York, Pennsylvania, Maryland, Ohio, Delaware and Illinois. The least density of population is in the mountain states, Nevada with less than one inhabitant to the square mile ranking the lowest, followed by Wyoming and Arizona. The largest percentages of increase are shown by the mountain and Pacific states, Washington leading with an increase of 120 per cent., followed by Oklahoma and Idaho. As has already been widely noted, Iowa shows an actual decrease in population. The states of Missouri and Indiana show very moderate increases; the rural New England states also show small increases of from four to seven per cent. The increase in New-York is 25 per cent, and in Pennsylvania 22 per cent.

The urban population, which includes j those residing in cities of 2,500 inhabitants or more, has increased 35 per j cent., and the rural population 11 per cent., seven tenths of the sixteen million increase being in the cities. The urban population is now 46 per cent.-of the total population, whereas in 1880 it was 29 per cent. The three cities—New York, Chicago and Philadelphia—having a population of more than one million, show thirty-two per cent, increase, while five cities, having a population of 500,000 to one million, show an increase of only 20 per cent. The cities—90 in number—having a population of 50,000 to 250,000 show the largest percentage of increase, namely,. 41 per cent. In New England and the Atlantic states about three quarters of the people live in the cities.

 

THE ERADICATION OF HOOKWORM DISEASE

The second annual report of the Rockefeller Sanitary Commission tells the story of a dramatic achievement of modern sanitary medicine. It will be remembered that the existence of hookworm disease in the south was not suspected until recently. It has now been found to be extremely prevalent. In the infection survey of the commission 87 counties were covered, 37,267 children examined, and the percentage of infection by counties was found to range from 2.5 to 90.2 per cent. In some schools practically every child was infected, and a large percentage of all children were unable to attend school. The disease is particularly disastrous in its consequences, for though not ordinarily fatal, like malaria it prevents