degree of refinement. In other words, when does a dwelling centre cease to be rural and become urban?
One method of studying the spatial relations of men and communities to one another is by measuring the density of population; the more human beings to the square mile, the closer together must be their habitations. The limitations upon the use of this method are, however, very considerable. Given two districts of equal population and territorial extent, there will be equal density; but in one case, the population may be scattered in small communities, and in the other congregated in a few large centres. In the latter case the average density will not be a true average; for example, to say that the average number of persons to the square kilometer in the province of Brandenburg, including the city of Berlin, is 112, is to give a ratio that is true neither of the rural part of the province (70) nor of Berlin itself (26,456). And when it is said that in California there are 7.78 persons to the square mile, in New Hampshire 41.81, it does not follow that in California the people are scattered and in New Hampshire agglomerated. On the contrary, 41 per cent. of the Californians dwell in towns of 10,000 or more inhabitants, and in New Hampshire only 25 per cent. Or compare Eng-
- Cf. Willcox, "Density and Distribution of Population in the United States at the Eleventh Census," Economic Studies of Amer. Econ. Ass'n., ii, 395.
- Table CXV, infra. Objection may be made to the use of California in such
comparisons, since its average density is not a true average. But no such objection can be raised against Iowa, which, as Prof. Willcox says, (op. cit., 418), "is
perhaps the most evenly settled State in the Union as measured by the mean variation of the densities of population of its counties from the State average." Vermont and Mississippi also have small percentages of variation, yet how different the distribution of population!
Table I. Density. Per cent. of population in cities of 10.000+. Missouri 38.98 25.59 Vermont 36.39 7.93 Iowa 34.47 13.62 Mississippi 27.83 2.64 United States 17.99 27.59