Carroll County is a county located in the U.S. state of Maryland. As of the 2020 census, the population was 172,891. Its county seat is Westminster. The county is part of the Central Maryland region of the state. Carroll County is included in the Washington-Baltimore-Arlington, DC-MD-VA-WV-PA Combined Statistical Area. While predominantly rural, the county …Carroll County is a county located in the U.S. state of Maryland. As of the 2020 census, the population was 172,891. Its county seat is Westminster. The county is part of the Central Maryland region of the state. Carroll County is 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.