United States Military Railroad

Reporting mark: USMRR
Existed during the Civil War from 18621865

Colonial Parkway Naval Access Bridge (York County, Virginia)
Built 1962
Slab bridge over North Pier Naval Access road and railroad on Colonial Parkway
Open to traffic above; authorized military traffic only underneath

USMRR - Potomac River Bridge (Old) (Prince George's County, Maryland)
Built 1864
Lost Bridge over Potomac River
Replaced by a new bridge