The B&P Tunnel system was completed in 1873, running under several West Baltimore neighborhoods including Bolton Hill, Madison Park, and Upton. The tunnel connects Baltimore's Pennsylvania Station to points south including Washington, DC. It is one of the oldest structures on the Northeast Corridor. The tunnel is approximately 7,500 feet (1.4 miles) long and is comprised of three shorter tunnels: the John Street Tunnel, the Wilson Street Tunnel, and the Gilmor Street Tunnel. The narrow-profile, single-bored, double-track tunnel was originally constructed out of brick and stone masonry, though repairs have added additional building materials over time. Electrification was added in the 1930s, and the tunnel was rehabilitated in the 1980s. However, that work was not intended as a permanent fix and continual repairs are required to maintain the aging structures.
The B&P Tunnel is a crucial link in the greater NEC Main Line, which runs through eight states and Washington, DC. The majority of the NEC was built between 1830 and 1917 by the Pennsylvania Railroad and the New York, New Haven and Hartford Railroad companies. The rail corridor came under the control of one owner, Penn Central, in 1969. Penn Central went bankrupt shortly thereafter, and Amtrak began operations in 1971. Currently, the fully electrified NEC provides a direct connection between Washington, DC, Baltimore, Philadelphia, New York, and Boston. Its 457 miles of rail move over 200 million passengers and an estimated 350,000 annual carloads of freight cargo each year. The NEC is a shared resource used by eight commuter rail operators, Amtrak, and four freight railroads.