: www.naperville.il.us Naperville is a city in DuPage and Will counties in the U.S. state of Illinois; it was voted the second-best place to live in the United States by Money magazine in 2006. As of the 2010 census, the city had a total population of 141,857. It is the fifth-largest city in the state, behind Chicago, neighboring Aurora, Rockford, and Joliet. Approximately 100,000 Napervillians live in DuPage County, while about 45,000 reside in Will County. Once a quaint farming town, Naperville has evolved into an affluent city with numerous corporate headquarters located in the city. In a 2010 study, Naperville was named as the wealthiest city in the Midwest and eleventh in the nation with a population over 75,000.