Irwin, IL has a population of 79 and is the 27,429th largest city in the United States. The population density is 2,027 per sq mi which is 812% higher than the Illinois average and 2137% higher than the national average. The median age in Irwin is 37 which is approximately 1% lower than the Illinois average of 37. In Irwin, 54% of the population over 15 years of age are married, 100% speak English and 0% speak Spanish. 85% of Irwin residents were born in Illinois, 15% were born out of state, 0% were born outside of the United States and 0% were foreign born.