The difference between a supersaturated manufacturing population and an undersaturated agricultural one, is expressed in the proportion of the population in the towns. Western Europe is a huge manufacturing city. In England, for instance, seventy-one per cent, of the people are urban, while in Russia only fifteen per cent., and in the United States it is about fifty per cent.*

In the United States during the nineteenth century the urban population increased fifteen fold, while the city population increased 150 fold. There were but sixteen cities of over 4,000 in 1800, but in 1900 there were 1,084. The twenty largest towns then held 250,000, the largest twenty now hold 12,000,000. Though the greatest per cent, of increase has been in the States still being settled in the West, the next greatest have been the manufacturing ones, and the States can be approximately thus divided into three groups: new, manufacturing, and old. In the middle group there is the greatest density per mile, largest number of cities, and most of the supersaturation.

* "The population of the rural districts of England is beginning to cause serious concern to the government. From statistics recently collated it is learned that in 1801, 36 per cent, of the population lived in towns of 1,000 inhabitants and upward, whereas in 1891, 64 per cent, of the population inhabited towns exceeding 4,000 in population. The rural population in 1891 on 31,577,000 acres was only 5,534,000 persons out of a total population of 29,002,525. It will be seen from these latter figures that less than one-fifth of the whole people live in the country and are engaged in rural occupations".

Bulletin four of the 1900 census of the United States mentions several facts which have a distinct bearing upon the saturation point of a country which is being filled up with a new civilization. For instance, Argentine is the only country which has a more rapid growth than that of the United States, which is double the average of Europe; nearly double that of Canada, one-sixth greater than Mexico, and one-tenth more than that of Australia. Our highest rates of increase are in the West, of course, yet the South has a greater rate than the North. Nevertheless, there is cumulating evidence that in all parts of the country the rates are approaching an equality, that is, the country is approaching saturation and the rate of increase is proportional to the increased food production. Moreover, the rates of increase on the two sides of the Atlantic are now approaching an equality for the same reason.