There are 18 US Post Offices in Lenawee County serving a total of 99,681 residents equating to 5,538 residents per post office. It's estimated that approximately 159,102 packages are handled across the 18 county post offices annually. Lenawee County (\"LENN-a-way\") is a county located in the U.S. state of Michigan. As of the 2010 census, the population was 99,892. The county seat is Adrian. The county was created in 1822 and organized in 1826. Lenawee County comprises the Adrian, MI Micropolitan Statistical Area and is included in the Detroit-Warren-Ann Arbor, MI Combined Statistical Area."