There are 8 US Post Offices in Carroll County serving a total of 158,337 residents equating to 19,792 residents per post office. It's estimated that approximately 252,724 packages are handled across the 8 county post offices annually. Carroll County is a county located in the U.S. state of Maryland. As of the 2010 census, the population was 167,134. Its county seat is Westminster. Carroll County is included in the Baltimore-Columbia-Towson, MD Metropolitan Statistical Area, which is also included in the Washington-Baltimore-Arlington, DC-MD-VA-WV-PA Combined Statistical Area. While predominantly rural, the county has become increasingly suburban in recent years."