Ask the Chatbot Games & Quizzes History & Society Science & Tech Biographies Animals & Nature Geography & Travel Arts & Culture ProCon Money Videos
Frederick
Introduction References & Edit History Related Topics
Images
Locator map of Frederick County, Maryland.
Britannica AI Icon
Adding us as a Preferred Source tells Google you trust our content, so our articles show up more often in your Google Search, Discover feed, and AI Overviews.
verifiedCite
While every effort has been made to follow citation style rules, there may be some discrepancies. Please refer to the appropriate style manual or other sources if you have any questions.
Select Citation Style
Feedback
Corrections? Updates? Omissions? Let us know if you have suggestions to improve this article (requires login).
Thank you for your feedback

Our editors will review what you’ve submitted and determine whether to revise the article.

External Websites
Locator map of Frederick County, Maryland.

Frederick

county, Maryland, United States
Written and fact-checked by
Britannica Editors
Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree....
Britannica Editors
Last updated
•History

News •

In increasingly blue Frederick County, voters echo national anger, calls for change • Nov. 5, 2026, 6:09 PM ET (The Baltimore Banner)
From Frederick to the Eastern Shore, blue wave expands Democrats’ reach • Nov. 4, 2026, 5:21 PM ET (The Baltimore Banner)
The lackluster Democratic campaign to defeat Frederick County’s MAGA sheriff • Oct. 31, 2026, 5:30 AM ET (The Baltimore Banner)
Data centers promised to transform Frederick County. They tore it apart instead. • Oct. 28, 2026, 3:00 AM ET (The Baltimore Banner)

Frederick, county, northern Maryland, U.S., bounded by Pennsylvania to the north, the Monocacy River to the northeast, Virginia to the southwest (the Potomac River constituting the border), and the Blue Ridge Mountains to the west. It consists of a piedmont region bisected north-south by the valley of the Monocacy. Parklands include Cunningham Falls State Park and Catoctin Mountain (national) Park, site of the Camp David presidential retreat. The Appalachian National Scenic Trail follows the ridgeline along much of the county’s western border. The county was created in 1748 and named for Frederick Calvert, 6th Baron Baltimore. Frederick, the county seat, is located a few miles north of the site of the Battle of Monocacy (July 9, 1864) of the American Civil War.

Principal economic activities are agriculture (corn [maize], hay, and dairy products) and manufacturing. Frederick has the largest area of any county in the state. Area 663 square miles (1,717 square km). Pop. (2000) 195,277; (2010) 233,385.

This article was most recently revised and updated by Chelsey Parrott-Sheffer.
Discover the fascinating events that shaped the world, straight from our editors.
By clicking “Sign Up”, you consent to the Britannica Privacy Policy and Terms of Use.