Maryland
- Altamont Tunnel, CSX near Deer Park
- Baltimore and Potomac Tunnel (B&P Tunnel), Pennsylvania Railroad, Baltimore
- Baltimore Harbor Tunnel, Baltimore, Interstate 895
- Borden Tunnel, Western Maryland Railway near Frostburg
- Brush Tunnel, Western Maryland Scenic Railroad near Corriganville
- Catoctin Tunnel, CSX near Point of Rocks
- Chesapeake and Ohio Canal National Historical Park road culverts:
- - #3 mile 11.?, Carderock, Potomac (1 & 2 are in DC)
- - #4 mile 109.?, Four Locks, near Williamsport
- Dalecarlia Tunnel, Baltimore and Ohio Railroad, Brookmont
- Fort McHenry Tunnel, Baltimore, Interstate 95
- Graham Tunnel, Baltimore and Ohio Railroad (CSX), Magnolia Cutoff, Allegany County, through same ridge as Kessler Tunnel (Western Maryland Railway) and Paw Paw Tunnel (C&O Canal)
- Henryton Tunnel, CSX, Marriottsville
- Oldest operating railroad tunnel in the country, third in the world
- Howard Street Tunnel, CSX, Baltimore
- Ilchester Tunnel, CSX, near Ellicott City
- Indigo Tunnel, Western Maryland Railway near Little Orleans
- Kessler Tunnel, Western Maryland Railway, Green Ridge State Forest in Allegany County
- Mt. Airy Tunnel, CSX, Ridgeville
- Paw Paw Tunnel, 3,118 feet (950 m), Chesapeake and Ohio Canal, across the Potomac from Paw Paw, West Virginia
- Point of Rocks Tunnel, CSX, Point of Rocks
- Stickpile Tunnel, Western Maryland Railway, Green Ridge State Forest
- Union Tunnel, Amtrak, Baltimore
- Wisconsin Avenue Tunnel, Baltimore and Ohio Railroad, Bethesda
Read more about this topic: List Of Tunnels In The United States