Chicago was organized as a Town in 1833 and Incorporated as a city in 1837. Chicago was ideally situated to take advantage of the trading possibilities created by the nation’s westward expansion. The completion of the Illinois & Michigan Canal in 1848 created a water link between the Great Lakes and the Mississippi River, but the canal was soon rendered obsolete by railroads. Today, 50 percent of U.S. rail freight continues to pass through Chicago, even as the city has become the nation’s busiest aviation center, thanks to O’Hare
and Midway International airports.