There are 16 US Post Offices in Kankakee County serving a total of 112,703 residents equating to 7,044 residents per post office. It's estimated that approximately 179,887 packages are handled across the 16 county post offices annually. Kankakee County is a county located in the U.S. state of Illinois. According to the 2010 census, it has a population of 113,449. Its county seat is Kankakee. Kankakee County comprises the Kankakee, IL Metropolitan Statistical Area, which is included in the Chicago-Naperville, IL-IN-WI Combined Statistical Area."