Dupo is a city located in St. Clair County Illinois. With a 2020 population of 3,789, it is the 378th largest city in Illinois and the 5555th largest city in the United States . Dupo is currently declining at a rate of -1.15% annually and its population has decreased by -8.43% since the most recent census, which recorded a population of 4,138 in 2010. Dupo reached it's highest population of 4,176 in 2010. Spanning over 6 miles, Dupo has a population density of 594 people per square mile.
The average household income in Dupo is $56,926 with a poverty rate of 20.19%. The median rental costs in recent years comes to $863 per month, and the median house value is $79,700. The median age in Dupo is 40.1 years, 37.3 years for males, and 44.3 years for females.