CHICAGO AND OTHER CITIES OF THE LAKE BASIN 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 arc 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 are 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 18 cities is 2,334,907, 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 18 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.