Flanagan, IL has a population of 1,069 and is the 14,734th largest city in the United States. The population density is 1,855 per sq mi which is 734% higher than the Illinois average and 1947% higher than the national average. The median age in Flanagan is 45 which is approximately 21% higher than the Illinois average of 37. In Flanagan, 67% of the population over 15 years of age are married, 96% speak English and 2% speak Spanish. 82% of Flanagan residents were born in Illinois, 16% were born out of state, 0% were born outside of the United States and 2% were foreign born.