Winnebago 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 278,418 people, with a population density of about 541.67 persons per square mile.
The county spans a total land area of 514.00 square miles (1,331.00 square kilometers). The administrative center and county seat is Rockford, which often serves as a hub for local governance and services. The largest city within the county by population is Rockford.
Geographically, Winnebago County experiences varied elevations, with its highest point at Lake Summerset 900 ft and its lowest point at Machesney Park 727 ft. The region operates in the UTC-6.