Effingham, IL has a population of 12,650 and is the 3,281st largest city in the United States. The population density is 1,244 per sq mi which is 460% higher than the Illinois average and 1273% higher than the national average. The median age in Effingham is 37 which is approximately 2% lower than the Illinois average of 37. In Effingham, 54% of the population over 15 years of age are married, 95% speak English and 2% speak Spanish. 80% of Effingham residents were born in Illinois, 17% were born out of state, 1% were born outside of the United States and 3% were foreign born.