There are 28 US Post Offices in Lake County serving a total of 737,817 residents equating to 26,351 residents per post office. It's estimated that approximately 1,177,638 packages are handled across the 28 county post offices annually. Lake County is a county in the northeastern corner of the U.S. state of Illinois. According to the 2010 census, it has a population of 703,462, making it the third-most populous county in Illinois. Its county seat is Waukegan. Originally part of McHenry County, the townships composing Lake County were carved out into a separate county in 1839. Lake County is one of the collar counties of the Chicago-Naperville-Elgin, IL-IN-WI Metropolitan Statistical Area. It is located along the shore of Lake Michigan. According to the 2000 census, Lake County is the 31st richest county by per capita income. The lakefront communities of Lake Forest, Lake Bluff, and Highland Park are part of the affluent North Shore area. Naval Station Great Lakes is located in the city of North Chicago in Lake County. It is the United States Navy's Headquarters Command for training, and the Navy's only recruit training center."