Frederick County is located in Maryland. The region is located on the body of water Potomac River. About 271,717 people live here (as of 2020). Between 2010 and 2020, the population grew from 233,385 to 271,717. The area covers about 1,728.0 square kilometers. The region is divided into 11 Municipalities. The region was founded in 1748. The postal codes are 21701–21705, 21709, 21701, 21703. The dialing code is 301. Frederick County is county in Maryland, United States. More information at
FrederickCountyMD.gov.