is a city in Will
and Kendall Counties
in the U.S. state
, 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.