Cityscape
After building the first ever skyscraper (Home Insurance Building), Chicago has been at the forefront of skyscraper building ever since. Today Chicago can boast to having 4 of the 10 tallest buildings in the United States and 9 of the 100 in the world.
By modern standards, Chicago has little reason to build up: being located in the Midwest, it has plenty of room to sprawl outwards on almost Euclideanesque flat ground. There is the Chicago River, which may bring some argument as to geographic restriction, but the impact of which was strongly lessened by the strict adherence to the Chicago grid across the river.
Today, Chicago is going through a massive skyscraper building boom, with projects like 55 East Erie (the tallest residential building in the U.S. outside New York City) and Trump International Hotel (completed in August 2008, it is the second tallest in Chicago and the tallest building built in the U.S. for nearly three decades) breaking ground frequently. All this can really be attributed to precedent: Chicago has always had a history of frantic skyscraper building, mostly beginning after the Great Chicago Fire when the price of land in the city increased. This caused architects to start building upward. Since this time developers simply follow the pattern set before them.
Read more about this topic: Geography Of Chicago