Forreston, IL has a population of 1,771 and is the 11,737th largest city in the United States. The population density is 1,961 per sq mi which is 782% higher than the Illinois average and 2065% higher than the national average. The median age in Forreston is 38 which is approximately equal to the Illinois average of 37. In Forreston, 64% of the population over 15 years of age are married, 99% speak English and 1% speak Spanish. 76% of Forreston residents were born in Illinois, 24% were born out of state, 0% were born outside of the United States and 0% were foreign born.