There are 13 US Post Offices in Lee County serving a total of 36,720 residents equating to 2,825 residents per post office. It's estimated that approximately 58,609 packages are handled across the 13 county post offices annually. Lee County is a county located in the U.S. state of Illinois. According to the 2010 census, it has a population of 36,031. Its county seat is Dixon. The Dixon, IL Micropolitan Statistical Area includes all of Lee County."