There are 4 US Post Offices in Kalkaska County serving a total of 17,255 residents equating to 4,314 residents per post office. It's estimated that approximately 27,541 packages are handled across the 4 county post offices annually. Kalkaska County is a county located in the U.S. state of Michigan. As of the 2010 census, the population was 17,153. The county seat is Kalkaska. Kalkaska County is included in the Traverse City Micropolitan Statistical Area. The county is considered to be part of Northern Michigan."