Caseyville, IL has a population of 4,263 and is the 7,154th largest city in the United States. The population density is 592 per sq mi which is 166% higher than the Illinois average and 553% higher than the national average. The median age in Caseyville is 38 which is approximately 1% higher than the Illinois average of 37. In Caseyville, 53% of the population over 15 years of age are married, 94% speak English and 6% speak Spanish. 67% of Caseyville residents were born in Illinois, 28% were born out of state, 0% were born outside of the United States and 5% were foreign born.