Maryland county map

How Maryland’s counties are laid out

Maryland’s counties are among the oldest in the country. St. Mary’s County was set up in 1637, three years after the first colonists landed at St. Clement’s Island, and Kent, Anne Arundel, Calvert and Charles followed by 1658. Every county except Garrett (1872) and Howard (1851) existed before the American Revolution, and the Eastern Shore counties — Kent, Talbot, Somerset, Dorchester, Cecil, Queen Anne’s, Worcester, Caroline — still carry the names of 17th-century English nobility and the Calvert family’s patrons.

The Chesapeake Bay splits the state into two halves. Nine counties on the Eastern Shore share the Delmarva Peninsula with Delaware and Virginia; the rest lie on the Western Shore, in the Baltimore–Washington corridor, or in the narrow panhandle that runs west along the Potomac to Garrett County. Four counties — Montgomery, Prince George’s, Baltimore and Anne Arundel — hold about 55 percent of the state’s 6.2 million people.

Baltimore City separated from Baltimore County in 1851 and is an independent city: it belongs to no county, elects its own government and is counted by the Census Bureau as a county equivalent. The county named Baltimore has its seat at Towson, not in the city, and the two are often confused. Maryland is entirely on Eastern Time.

All 24 counties of Maryland

Five county facts

• Largest by area: Frederick County, seat Frederick, about 660 square miles of land between the Monocacy River and the Catoctin and South Mountain ridges. Garrett County at the far western end is only slightly smaller; Dorchester on the Eastern Shore is larger if its bay water is counted.
• Smallest by area: Baltimore City, about 80 square miles of land. Among the counties proper, Calvert County, a peninsula between the Patuxent River and the Chesapeake, is the smallest at about 210 square miles of land, and the smallest by population on the Western Shore.
• Most populous: Montgomery County, seat Rockville, with about 1.06 million people in 2020; it borders Washington, DC and includes Silver Spring, Bethesda and Gaithersburg. Prince George’s County is second at about 967,000, Baltimore County third at about 854,000, and Baltimore City fourth at about 586,000, down from nearly 950,000 in 1950.
• Least populous: Kent County, seat Chestertown, on the upper Eastern Shore, with about 19,000 people. Somerset County at the southern tip of the Eastern Shore and Garrett County in the mountains are next.
• Oldest and newest: St. Mary’s County (1637) is the oldest. Garrett County, seat Oakland, was cut from Allegany in 1872 and is the newest. Baltimore is the only independent city in Maryland and, apart from St. Louis and Carson City, the only one outside Virginia.

Reading the map

Press Streets and zoom in to see county lines. The Potomac River is the southern border of Garrett, Allegany, Washington, Frederick, Montgomery, Prince George’s, Charles and St. Mary’s counties, with the river itself belonging to Maryland up to the Virginia low-water mark. The Mason–Dixon Line is the straight northern edge of every county from Garrett to Cecil. Washington County at Hancock narrows the state to less than two miles wide between the Potomac and Pennsylvania. The capital, Annapolis, is the seat of Anne Arundel County on the Severn River near the Chesapeake Bay Bridge, which links it to Queen Anne’s County on the Eastern Shore.

Related maps

• Maryland map — cities, borders and geography.
• Blank Maryland map and printable Maryland map.
• Annapolis, the state capital; Baltimore, the largest city; Washington, DC.
• Neighbouring county maps: Pennsylvania, Delaware, Virginia, West Virginia.
• South Atlantic states · the South · Mid-Atlantic · Eastern Time Zone.
• Geography: Mason–Dixon Line, Appalachian Mountains, US coastlines.
• All US county maps.