Darien is a city located in DuPage County, Illinois, within the United States. It serves as a southwestern suburb of Chicago and was named after the town of Darien, Connecticut.
The city's geography is defined by its proximity to major transportation routes, situated just north of Interstate 55 and Historic U.S. Route 66. The southern edge of the town borders Waterfall Glen. According to the 2020 census, Darien had a population of 22,011.