Casey, IL has a population of 2,561 and is the 9,704th largest city in the United States. The population density is 1,200 per sq mi which is 440% higher than the Illinois average and 1224% higher than the national average. The median age in Casey is 41 which is approximately 10% higher than the Illinois average of 37. In Casey, 58% of the population over 15 years of age are married, 95% speak English and 4% speak Spanish. 59% of Casey residents were born in Illinois, 39% were born out of state, 0% were born outside of the United States and 2% were foreign born.