In 1866 the Canton Company of Baltimore obtained a charter from State of Maryland to build the Union Railroad.[1] Active steps to finance construction of the railroad and tunnel came only in the autumn of 1870, and actual construction began on May 1, 1871. On July 24, 1873, the first train passed through the tunnel.[3][4] The original tunnel began at Bond Street, and passed under the bed of Hoffman Street to Greenmount Avenue, crossing under Dallas, Caroline, Spring and Eden Streets, Central and Harford Avenues, and Ensor, Valley and McKim Streets. Its length is 3,410 feet (1,040 m). The total cost of the road and tunnel was some $3,000,000.[4]
As soon as the Union Railroad was completed, the Northern Central Railway obtained the right to use it, and in February, 1882, the Northern Central purchased the Union Railroad stock from the Canton Company, and assumed control March 1 of the same year.[4]
Modifications
Additional work was done on the tunnels between 1928 and 1935 to prepare for the electrification of the Pennsylvania Railroad's New York-Washington mainline. The original Union Tunnel, too small to accommodate overhead catenary on its two tracks, was supplemented by an adjacent double-track tunnel to the east, then converted to a single track which provided adequate clearance for electrification.
39°18′21″N76°36′32″W / 39.3058°N 76.6088°W / 39.3058; -76.6088