Oblong, IL has a population of 1,571 and is the 12,429th largest city in the United States. The population density is 1,416 per sq mi which is 537% higher than the Illinois average and 1463% higher than the national average. The median age in Oblong is 42 which is approximately 13% higher than the Illinois average of 37. In Oblong, 59% of the population over 15 years of age are married, 99% speak English and 0% speak Spanish. 79% of Oblong residents were born in Illinois, 21% were born out of state, 0% were born outside of the United States and 0% were foreign born.