The Wilkes Street Tunnel was part of the Orange & Alexandria Railroad, founded in 1848 to promote trade with western Virginia. The Orange and Alexandria inaugurated its track in Alexandria on May 7, 1851 with a run to the north end of Union Street to the Wilkes Street Tunnel. Thus, the tunnel linked the railroad to warehouses and wharves along the waterfront. Located nearby, the Smith and Perkins foundry manufactured locomotives for the Orange and Alexandria and other railroads.
Wilkes Street Tunnel is typical of cut-and-cover tunnel construction. Presumably, the tunnel was cut through the bluff overlooking the Potomac River and covered to continue the streets above. After the sides were built up with stone, the arch probably was constructed over wood falsework from both sides using a centering technique to form the brick barrel vault. The tunnel was deepened after World War I to accommodate higher boxcars.
The Orange and Alexandria line was one of the many Alexandria railroads taken over by Union forces at the onset of the Civil War. While this northerly section of the railroad was incorporated into the U.S. Military Railroads, the length of track south of the Rappahannock River remained in Confederate hands.
Both sections played an major role in the strategies of North and South, as well as a decisive element in the Confederate victory at the Second Battle of Manassas or Bull Run. The Wilkes Street Tunnel gave Union Army access to the wharves for shipping military supplies on car ferries south of Aquia Creek, terminus of the Richmond, Fredericksburg & Potomac Railroad.
Shortly after the Civil War, the old Orange & Alexandria line was incorporated into the Washington City, Virginia Midland & Great Southern Railway controlled by the Baltimore & Ohio Railroad. Wilkes Street Tunnel played a part in the rivalry between the Baltimore & Ohio and Pennsylvania Railroads for supremacy in the north-south trade across the Potomac River. The Pennsylvania Railroad acquired Congressional authorization for exclusive use of Long Bridge (14th Street). To maintain a competitive position, Baltimore & Ohio offered trans-Potomac service by way of carfloats linking Wilkes Street with Shepherd's Ferry on the Maryland shore until about 1906.
The Wilkes Street track continued in operation until 1975 when declining industrial activity along the waterfront no longer warranted rail service. The tunnel is significant today as Alexandria's only 19th century transportation site surviving intact.