Joliet is a city in Will and Kendall Counties in the U.S. state of Illinois, located 40 miles (64 km) southwest of Chicago. It is the county seat of Will County. As of the 2010 census, the city was the fourth-most populated in Illinois, with a population of 147,433. It continues to be Illinois' fastest growing city and one of the fastest growing in the United States. When Joliet was first planned in the early 1830s, it was still in Cook County. In 1836, it became the county seat of the new Will County.
In 1833, following the Black Hawk War, Charles Reed built a cabin along the west side of the Des Plaines River. Across the river in 1834, James B. Campbell, treasurer of the canal commissioners, laid out the village of "Juliet", named after his daughter. Just before the depression of 1837, Juliet incorporated as a village, but to cut tax expenses, Juliet residents soon petitioned the state to rescind that incorporation. In 1845, local residents changed the community's name from "Juliet" to "Joliet". Joliet was reincorporated as a city in 1852. The origin of the name was most likely a corruption of the name of French Canadian explorer Louis Jolliet, who in 1673, along with Father Jacques Marquette, paddled up the Des Plaines River and camped on a huge mound, a few miles south of present-day Joliet. Maps from Jolliet's exploration of the area, placed a large hill or mound on what is now the southwest corner of the city. That hill was named Mound Jolliet and was made up entirely of clay. The spot was mined by early settlers and is now a depression.
Joliet is located at 41°31?21?N 88°08?26?W / 41.5225°N 88.14056°W / 41.5225; -88.14056 (41.5224597, -88.1406140).