The Chicago Region
Cook County encompasses more than 1,600 square miles in northeastern Illinois. It extends about forty miles north to south and stretches westward about thirty miles from Lake Michigan to the Fox River Valley. As of 1900, the county’s population was 1,838,735 (compared with more than five million today), and more than 90 per cent of the population resided in the city of Chicago.
Much of the outlying county land was fallow or dotted by farms, small towns, or villages. The largest suburbs at that time were found along the North Shore of Lake Michigan and included Winnetka, Wilmette, and Kenilworth. Other settlements straddled major rail lines in the region. Among them were Arlington Heights, Palatine, Elmhurst, Riverside, La Grange, Summit, Oak Lawn, Blue Island, and Harvey. The suburban enclaves of Evanston, Oak Park, and Cicero bordered on the city of Chicago and grew rapidly during the early twentieth century.
The county presented a diverse set of ecologies:
- Starting in the northeastern section of the county, the Skokie River creates a broad wetland and marsh just west of the affluent towns of Winnetka, Wilmette, and Evanston.
- The Des Plaines River and the North Branch of the Chicago River flow south, west of the Skokie River.
- Near downtown Chicago, the Chicago River turns toward Lake Michigan while the Des Plaines flows still farther along a path almost parallel to the Lake Michigan shoreline, passing just to the west of the suburbs of Oak Park, Cicero, and Riverside.
- Southwest of Chicago's downtown, near 47th Street and Harlem Avenue, lies the historic Chicago portage. This low area forms a sub-continental divide between the Great Lakes and the Mississippi Valley. Near the portage, the Des Plaines curves toward the southwest as it flows alongside the Chicago Sanitary and Ship Canal. Completed in 1900, the canal diverted;stormwater and sewage from Lake Michigan and improved transportation capacity.
- The southern portion of Cook County includes the Calumet River and the Sanitary and Ship canal.
