Mason 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 16,038 people, with a population density of about 29.76 persons per square mile.
The county spans a total land area of 539.00 square miles (1,396.00 square kilometers). The administrative center and county seat is Havana, which often serves as a hub for local governance and services. The largest city within the county by population is Havana.
Geographically, Mason County experiences varied elevations, with its highest point at Mason City 575 ft and its lowest point at Bath 462 ft. The region operates in the UTC-6.