There are 5 US Post Offices in Dearborn County serving a total of 44,276 residents equating to 8,855 residents per post office. It's estimated that approximately 70,669 packages are handled across the 5 county post offices annually. Dearborn County is a county located in the U.S. state of Indiana. As of 2010, the population was 50,047. The county seat and largest city is Lawrenceburg. Dearborn County is part of the Cincinnati-Middletown, OH-KY-IN Metropolitan Statistical Area."