Farmington, IL has a population of 2,512 and is the 9,823rd largest city in the United States. The population density is 1,738 per sq mi which is 662% higher than the Illinois average and 1818% higher than the national average. The median age in Farmington is 38 which is approximately 1% higher than the Illinois average of 37. In Farmington, 61% of the population over 15 years of age are married, 99% speak English and 0% speak Spanish. 89% of Farmington residents were born in Illinois, 9% were born out of state, 1% were born outside of the United States and 1% were foreign born.