Dupo, IL has a population of 3,966 and is the 7,487th largest city in the United States. The population density is 630 per sq mi which is 183% higher than the Illinois average and 596% higher than the national average. The median age in Dupo is 36 which is approximately 4% lower than the Illinois average of 37. In Dupo, 50% of the population over 15 years of age are married, 96% speak English and 3% speak Spanish. 54% of Dupo residents were born in Illinois, 45% were born out of state, 0% were born outside of the United States and 1% were foreign born.