Forrest, IL has a population of 1,083 and is the 14,642nd largest city in the United States. The population density is 1,608 per sq mi which is 623% higher than the Illinois average and 1674% higher than the national average. The median age in Forrest is 36 which is approximately 4% lower than the Illinois average of 37. In Forrest, 70% of the population over 15 years of age are married, 94% speak English and 5% speak Spanish. 83% of Forrest residents were born in Illinois, 13% were born out of state, 0% were born outside of the United States and 3% were foreign born.