Piatt County is a county located in the U.S. state of Illinois. As of the most recent data available, the county has a population of approximately 16,365 people, with a population density of about 37.19 persons per square mile.
The county spans a total land area of 440.00 square miles (1,140.00 square kilometers). The administrative center and county seat is Monticello, which often serves as a hub for local governance and services. The largest city within the county by population is Monticello.
Geographically, Piatt County experiences varied elevations, with its highest point at Cerro Gordo 742 ft and its lowest point at Monticello 675 ft. The region operates in the UTC-6.