Hagerstown is a city in and the county seat of Washington County, Maryland, United States. The population was 43,527 at the 2020 census. Hagerstown ranks as Maryland's sixth-most populous incorporated city and is the most populous city in the Maryland Panhandle. Hagerstown anchors the Hagerstown metropolitan area extending into West Virginia. It makes up the northwesternmost portion of the Washington–Baltimore combined statistical area in the heart of the Great Appalachian Valley.