There are 7 US Post Offices in Carroll County serving a total of 14,839 residents equating to 2,120 residents per post office. It's estimated that approximately 23,685 packages are handled across the 7 county post offices annually. Carroll County is a county located in the U.S. state of Indiana. As of 2010, the population was 20,155. The county seat is Delphi. Carroll County is part of the Lafayette, Indiana, Metropolitan Statistical Area."