Queen Anne's County is a county located in the U.S. state of Maryland. As of the 2020 census, the population was 49,874. Its county seat and most populous municipality is Centreville. The census-designated place of Stevensville is the county's most populous place with a population of 7,442 as of 2020. The county is named for Queen Anne of Great Britain, who reigned when the county was established in 1706 during the colonial period.