CHICAGO AND OTHER CITIES OF THE LAKE BARN Plan of treatment.—The United States census of 1910 gives for Illinois 144 cities having a population of 2,500 or more. There are several hundred smaller towns and villages with populations between 100 and 2,500. No attempt is here made to deal with individual cities in detail, but an effort is made to give a bird's-eye view of the cities of the state in their geographical setting with reference to each other and to the surface features of the state. To this end the cities are grouped according to the drainage basins described in chapter iv. Within the group the cities are mentioned in an order easily followed on the map. A few leading facts are given concerning many of the cities. All of the 144 cities having a population of 2,500 or more are referred to in the text, and in parentheses the population according to the census of 1910 is given. Many towns and villages with smaller populations arc mentioned with census figures inserted.
A region of urban population.—That part of the land surface of Illinois lying in the Lake Michigan Basin has an area of 722 square miles or 1.3 per cent of that of the state. This region comprises portions of Lake, Cook, and Will counties. The total area, however, is 211 square miles less than that of Cook County alone. The region is SO miles in its north-south extent, and it varies from 4 to 20 miles in width from the lake shore. On this area are found 18 of the 144 cities of the state large enough to be classified as "urban." The combined popu
lation (1910) of these IS cities is 2,334,967, or 67 per cent of the urban population of the state and 41 per cent of the total population of the state. In addition to these 1S cities, the region contains more than a score of other villages and small cities and hundreds of farms. The population of these villages and farms probably does not exceed 25,000, or about 1 per cent of the population of the basin.
Chicago alone, with its arca of 200 square miles, occupies more than one-fourth of the entire Lake Basin in Illinois. The population of Chicago (1910) comprises 93 per cent of the total of the 18 cities of this region, 63 per cent of the total urban population of the state, and 39 per cent of the entire population of the state. Chicago has an average of 11,000 per sons per square mile. The average density for the region of 722 square miles is 3,200 per square mile; for the area outside of Chicago 335 per square mile, or only one-half as great as the average density of the whole of England. The average density of the state as a whole is 100 per square mile; that part outside of the Lake Basin has a density of 59 per square mile. Thus the Lake Michigan shore of Illinois is pre eminently the urban district of the state, and if the lake shore is followed eastward beyond the state line its urban character is evidenced by the closely built cities of Lake County, Indiana.