
Monticello
- County:
- Piatt County
- County Seat:
- Yes
- Area (mi²):
- 3.878
- State:
- Illinois
Monticello is a city located in Piatt County, Illinois. Monticello has a 2025 population of 6,063. It is also the county seat of .Monticello is currently growing at a rate of 0.38% annually and its population has increased by 1.9% since the most recent census, which recorded a population of 5,950 in 2020.
The average household income in Monticello is $99,532 with a poverty rate of 6.14%. The median age in Monticello is 42.9 years: 40.7 years for males, and 45.9 years for females.