There are 24 US Post Offices in Kane County serving a total of 444,002 residents equating to 18,500 residents per post office. It's estimated that approximately 708,677 packages are handled across the 24 county post offices annually. Kane County is a county located in the U.S. state of Illinois. According to the 2010 census, it has a population of 515,269, making it the fifth-most populous county in Illinois. Its county seat is Geneva, and its largest city is Aurora. Kane County is one of the collar counties of the Chicago-Naperville-Elgin, IL-IN-WI Metropolitan Statistical Area."