The city of Chicago was built on very low ground, almost as low as Lake Michigan. This meant that throughout the 1800s the city had virtually no drainage. This caused a lot of sitting water, which made living conditions poor.
Diseases like dysentery and typhoid fever abounded, and the sitting water was blamed for the outbreak of cholera as well, which killed 6% of Chicago’s population at the time. The plan they came up with was to raise the city a few feet in order to provide some drainage area.
The first building to be raised was a masonry building on the corner of Randolph and Dearborn Street. It was raised with 200 jackscrews up 6 feet and 2 inches. The building was raised without being damaged at all. Boston engineer James Brown and Chicago engineer James Hollingsworth were in charge of raising that first house and would go on to raise many more. At one point they managed to raise a 200-foot building!
The city was also starting to bloom at the time. Many people didn't like the old, wood framed houses, considering them to be inappropriate for the increasingly wealthier city. Many houses weren't just raised, but also moved outside the city, something that was common in Chicago for the following years.