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 ( 2 tracks)
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