Jerseyville is the largest city in and the county seat of Jersey County, Illinois, United States. At the 2020 census, the city had a total population of 8,337.

The Metro East is an urban area in Southern Illinois, United States that contains the eastern and northern suburbs and exurbs of St. Louis, Missouri. It encompasses five counties in the Greater St. Louis area and constitutes the second-most populous urban area in Illinois. The region's most populated city is Belleville, with 42,404 residents.