Dupo is a village in St. Clair County, Illinois, United States. The population was 4,138 at the 2010 census, an increase from 3,933 in 2000. The village was settled in about 1750 and was incorporated in 1907. Its modern name, adopted in the early 20th century, is shortened from Prairie du Pont ("Bridge Prairie").
Zip Codes in Dupo, IL that we also serve: 62240 62236 62239