There are 22 US Post Offices in Genesee County serving a total of 326,229 residents equating to 14,829 residents per post office. It's estimated that approximately 520,698 packages are handled across the 22 county post offices annually. Genesee County is a county in the U.S. state of Michigan. As of the 2010 census, the population was 425,790, making it the fifth-most populous county in Michigan. The county seat and population center is Flint (birthplace of General Motors). Genesee County is considered to be a part of the greater Mid Michigan area. Genesee County comprises the Flint, MI Metropolitan Statistical Area and is included in the Detroit-Warren-Ann Arbor, MI Combined Statistical Area.