The 10 Longest Rivers in Maryland

Patuxent River is the longest and largest river entirely within the state of Maryland.
Patuxent River is the longest and largest river entirely within the state of Maryland.

Maryland is the birthplace of religious freedom in the United States and one of the original 13 colonies. Maryland has 23 counties, and 16 of them border Chesapeake Bay estuary and its branches (whose combined length is over 4,000 miles). The majority of the waterways within Maryland are part of Chesapeake Bay watershed, except for a small section on the western sides of Garrett County which belongs to Mississippi River’s basin. The longest river which is entirely within the state is Patuxent River.

The Longest Rivers in Maryland

1) Susquehanna River

The 464 mile long Susquehanna River is the longest East Coast River which empties into the Atlantic Ocean. It is the sixteenth largest river in the country and the longest American river which does not have commercial boats. It drains over 27,500 square miles of the watershed which includes over 50% of Pennsylvania. Its basin also includes parts of Allegheny Plateau. Susquehanna River empties into the Chesapeake Bay, and it supplies over half the water in the bay. It is formed by two tributaries, the west and the north branches, which merge near Northumberland, Pennsylvania.

2) Potomac River

The 405 mile long Potomac River has a watershed area of about 14,700 square miles. The river rises from Potomac Island and flows into the Chesapeake Bay. Potomac River is the twenty-first largest rivers in the country and the fourth in the Atlantic coast. Over five million Americans reside within its watershed. Potomac River is part of the Virginia-West Virginia and Washington D.C.-Maryland borders.

3) Youghiogheny River

Youghiogheny River is a 134 mile long river located in Pennsylvania, Maryland, and West Virginia. The river rises from Preston County near Backbone Mountain and flows into Monongahela River at McKeesport. The term "Youghiogheny" is a Lenape phrase which means "a stream which flows in a contrary direction.’’

4) Patuxent River

Patuxent is 115 miles long and is the longest and largest river which is within the state of Maryland. Its watershed is within Maryland and the river drains an area of about 937 square miles. The river serves as the boundary between Calvert, Anne Arundel, and Howard to the east and Montgomery, St Mary’s, Charles, and Prince George counties to the west.

5) North Branch Potomac River

The 106 mile long river originates from Fairfax Stone right at the junctions between Preston, Tucker, and Grant counties. It then flows through Lake Jennings Randolph and passes through numerous cities including Westernport, Luke, Bloomington, Cumberland, West Virginia, and Keyser. It then merges with the South Branch Potomac River right between South Branch Depot and Green Spring in West Virginia before flowing through Hancock to the Chesapeake Bay.

6) Conococheague Creek

The 80 mile long Conococheague Creek is a branch of River Potomac. It is a free-flowing river which rises from Pennsylvania and then flows to River Potomac. The river drains an area of about 566 square miles. The name "Conococheague" is an Unami-Lenape term which means "many-turns-river." Conococheague Creek serves as the boundary between Cumberland Valley and Hagerstown Valley.

7) Choptank River

Choptank River is the longest river in the Delmarva Peninsula and the main branch of Chesapeake Bay. The 71 mile long river originates from Kent County and flows through Maryland forming a bigger part of the boundary between Dorchester and Caroline counties. Choptank River drains an area of about 1,004 square miles in Maryland. The river starts at Choptank Mills and empties into the Chesapeake Bay.

Other Rivers in Maryland

The top ten longest rivers in Maryland are all over 58 miles long with Monocacy River ranking tenth. Monocacy River is one of the branches of Potomac Rivers which flows into the Atlantic Ocean. Pocomoke is a 66miles long river which stretches to Maryland from southern Delaware. The 64.3 mile long Nanticoke River is Chesapeake Bay’s tributary which is in the Delmarva Peninsula.

The 10 Longest Rivers in Maryland

RankRiverLength (miles)Length (km)
1Susquehanna River464747
2Potomac River302486
3Youghiogheny River 134216
4Patuxent River 115185
5North Branch Potomac River 103166
6Conococheague Creek 80130
7Choptank River 71114
8Pocomoke River66106
9Nanticoke River 64103
10Monocacy River5893

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