County facts · Land area · October 22, 2026

Largest Counties in Maryland by Area and Population

The largest Maryland counties by land area and by 2023 population, plus the smallest, county seats and a link to each official parcel map.

Looking for the largest counties in Maryland? Maryland has 23 counties plus 1 independent city, which sit outside any county and are counted by the Census Bureau as county equivalents. Together they cover about 9,711 square miles of land, based on the Census Bureau's 2020 Gazetteer. The largest by land area is Frederick County, at about 661 square miles, roughly 3.1 times the size of the smallest, Calvert County (213 sq mi). Measured by people instead, the largest is Montgomery County, with about 1,058,474 residents in the Census Bureau's July 1, 2023 estimate.

The rankings below compare counties with counties. The independent city is listed in its own section further down, but it is included in the statewide totals.

The tables below rank the counties both ways. Each row links to the county's Platbookmapper page and straight to its official parcel viewer.

Maryland counties at a glance

• Counties: 23, plus 1 independent city
• Land area: about 9,711 sq mi, plus about 2,695 sq mi of water inside county lines
• Residents, 2023 estimates: about 6,180,253, or about 636 people per square mile of land
• Median county land area: about 422 sq mi
• With a verified public parcel viewer in our directory: 24 of 24 (21 of them through a statewide viewer)

The 10 largest Maryland counties by land area

Together these 10 cover about 54% of Maryland's land area and hold about 61% of its residents.

The 10 most populous Maryland counties

These 10 hold about 78% of Maryland's residents in the 2023 estimates.

The 5 smallest Maryland counties by land area

Maryland's independent city

Baltimore City is not part of any county. It covers about 81 square miles of land and had about 565,239 residents in the 2023 estimate, about 6,983 people per square mile. Its official parcel map: Maryland FINDER Online (MD Dept. of Planning). Its Platbookmapper page: Baltimore City.

Most and least crowded

• Most people per square mile: Montgomery County, about 2,147 (then Prince George's County, 1,963, and Anne Arundel County, 1,433)
• Fewest people per square mile: Garrett County, about 44 (then Dorchester County, 61, and Kent County, 70)

Counties with the most water

The Census Bureau reports water separately from land. It counts lakes, reservoirs, rivers and, along a coast or a Great Lake, the water inside the boundary.

• Dorchester County: about 442 sq mi of water, 45% of its total area
• St. Mary's County: about 406 sq mi of water, 53% of its total area
• Somerset County: about 291 sq mi of water, 48% of its total area

Using these numbers in a land search

• Land area is not parcel count. A large rural county can hold fewer parcels than a small suburban one, so size alone says little about how busy its parcel map is.
• Search, don't scroll. In a big county, type an address, owner name or parcel number into the viewer's search box, where it has one, instead of panning across the map.
• Records follow the county line. Deeds, plats and tax bills are kept by the county where the parcel sits (or the independent city), so a tract that crosses a county line usually has a parcel number on each side.
• Rounded figures. Land and water areas are rounded to whole square miles (one decimal for very small places). People per square mile is the 2023 estimate divided by land area.

Related guides

• Maryland county GIS websites by viewer
• Maryland plat maps
• Maryland landowner maps for hunting
• Maryland–Pennsylvania border counties
• Maryland–Virginia border counties
• Largest county in each state
• Largest counties in the US by land area

More: All Maryland counties on Platbookmapper

Sources

• U.S. Census Bureau Gazetteer files, 2020 county land and water area.
• U.S. Census Bureau, Population Estimates Program, county totals, Vintage 2023 (July 1, 2023 estimates)
• Platbookmapper county GIS directory (live data file behind our county pages, pulled October 22, 2026) for each official parcel viewer.
• County seats: Wikidata (county seat property), cross-checked against Census place names.