Formed in 1839, DuPage County, Illinois, has an area of more than 300 square miles and provides a wide range of economic development and public welfare services for its residents. It has a population of more than 1 million people and is one of the most populous counties in Illinois. Its county seat is Wheaton, Ill. DuPage County is among the nine counties in Illinois that comprises the Chicago Primary Metropolitan Statistical Area, a group of counties with close economic and social ties to a central city. The county invests in various projects, including substantial roadways, utility infrastructure and other public improvement projects that had transformed it into a major employment and population center within the Chicago region. It offers a wide range of community services through colleges, public libraries, hospitals, park districts, forest preserve sites and golf courses.