Maryland Area Regional Commuter

Reporting mark: MARC
Amtrak - B&P Tunnels (Baltimore County, Maryland)
Built 1873
Tunnel under Baltimore, MD on Amtrak Northeast Corridor
Open to traffic

Amtrak - Gunpowder River Bridge (Baltimore County, Maryland)
Built 1912-13 one track at a time to replace wooden pile trestle
Girder bridge over Gunpowder River on Amtrak RR
Open to rail traffic, draw mechanism removed

Union Tunnel (Baltimore, Maryland)
First tunnel begun 1866, opened 1873; second bore completed 1934
Tunnel on Amtrak (former Penn Central/PRR)
Open to traffic