Alexandria Canal, Site 44AX0028
901 N. Pitt Street

Historic maps show that the ca. 1840 Alexandria Canal, specifically the fourth lock and third basin, lies beneath this portion of the city block bounded by Montgomery St., N. Pitt St., N. Royal St., and First St. Alexandria Archaeology anticipated that the masonry remains of this large-scale piece of historic infrastructure may be preserved despite 20th century development on the block. As part of the redevelopment of the Waterman Place office building, Carr Companies contracted with professional archaeologists from Thunderbird Archeology, a division of Wetlands Studies and Solutions, LLC, to implement an archaeological monitoring plan in accordance with the Alexandria Archaeological Protection Code. 

In the fall of 2024, a preliminary round of mechanical trenching exposed the north stone wall of the lock and basin. The south side of the lock wall appears to have been disturbed by the construction of the previous office building.

“The Alexandria Canal, begun more than 150 years ago as a seven mile segment in a regional commercial navigation system of 185 miles, helped to create and to shape regional growth patterns in and around Alexandria” (Hahn and Kemp 1992:xi).

The Potomac Company formed in 1785 with the goal of building a canal that would extend shipping traffic to western Maryland by circumventing the falls of the Potomac River. The Chesapeake and Ohio Canal Company took over the canal business in 1828, after the Potomac Company went out of business. The C&O Canal Company’s objective was to create a continuous canal that eventually stretched from Georgetown to Cumberland, Maryland. 

Alexandria’s merchants and shipowners sought to build an extension from the terminus of the canal at Georgetown to the port of Alexandria and profit from this access to western trade. This required the building of a1,000-foot-long aqueduct bridge over the Potomac River. On December 2, 1843, the Alexandria Canal was officially opened to trade and navigation and the first canal boat arrived at Alexandria. In 1845, the canal company completed construction of four lift locks and three basins or “pools” between the Potomac River and N. Pitt Street. 

In the years of operation before the Civil War, the Alexandria canal primarily shipped manufactured products and fish and received agricultural products. The majority of the descending, or incoming, cargo shifted after the opening of the C&O Canal to Cumberland, Maryland in 1850 from agricultural products to coal. The Alexandria Canal went dormant during the Civil War, disrupted by the movement of Union troops and supplies and the conversion of the aqueduct to a wagon road to facilitate that movement. The canal did reopen after the Civil War, but it was continually plagued by the need for expensive repairs. Ultimately, railroad transportation eclipsed the canal system and it was abandoned in 1886.

Remnants of the canal were visible on the landscape at least through 1937. In Virginia Knapper’s oral history, she shared her memories of the Black neighborhood known as Cross Canal and described what the canal looked like in the early 20th century. Knapper remembered a bridge across the canal and skating in her shoes where the water still formed and froze during the winter.  

Nearly 50 years ago, Alexandria archaeologists uncovered the outlet (or tide) lock and pool No. 1 at the mouth of the Potomac River. Over the course of about six years, archaeologists, the Alexandria Archaeological Commission, developers, and engineers worked together to excavate, repair, rehabilitate, and interpret the outlet lock, basin, and associated wing walls of the easternmost lock. The site was listed on the National Register of Historic Places in 1980. An interpretive reconstruction of the tide lock stands today as the centerpiece of Tide Lock Park, a privately owned, publicly accessible park that helps residents visualize and understand the city’s historic landscape.

As developers began planning for new construction at the 901 N. St Asaph St. block in 2015, Alexandria Archaeology determined that the property had the potential to yield archaeological resources that could provide insight into industrial and transportation activities in 19th-century Alexandria. A preliminary assessment anticipated that there might be remnants of the Alexandria Canal turning basin situated on this property. Additionally, there was a “Spa,” or spring, adjacent to the turning basin, to the west, near a stream on this property that appears on the 1845 Ewing Map. The 1877 Hopkins fire insurance map indicates that there was a lime kiln structure present on the site adjacent to the turning basin. Archaeologists on contract with the developers monitored the construction work on the block and documented soil layers associated with filling in the basin and the brick culvert associated with the Spa Spring.

• History of the Alexandria Canal. Brochure, Alexandria Archaeology Museum and Department of Planning.
• Old Town North Historic Interpretation Guide. Completed by the City of Alexandria, Office of Historic Alexandria, with assistance from PRESERVE/scapes and Stantec, 2017. 
• The Alexandria Canal: Its History and Preservation, Thomas Swiftwater Hahn and Emory L. Kemp. West Virginia University Press, 1992. 
• The Alexandria Canal. Marking Time, Alexandria Times, September 6, 2007.
• The Industrial Archaeology of the Tide Lock and Pool No. 1 of the Alexandria Canal. Thomas S. Hahn, 1982. (On file at Alexandria Archaeology Museum.)
• Maritime Historical Report for Alexandria Canal Tide Lock Project. Thomas S. Hahn, 1982. (On file at Alexandria Archaeology Museum.)
• A Canal for Alexandria. Alexandria History, volume 1, pp. 17-28. Vivienne Mitchell, 1978. 
• Alexandria Canal Tide Lock National Register Nomination.
• The Alexandria Canal: Tidewater Terminus of the Chesapeake and Ohio Canal System. Alexandria Archaeology Publications Number 22. Keith Barr, 1989.

Alexandria Canal (901 N. Fairfax Street)

• The Alexandria Canal Company, 1830-1886
• Cross Canal Neighborhood, 1860s - 1960s

Potomac Yard (2501 Potomac Avenue)

• Crossroads of Transportation.  Roads, passenger rail and the Canal also crossed through the Yard.

Alexandria Canal (525 Montgomery Street) 

• Alexandria Canal Turning Basin (1843-1886)
• The Tale of Spa Spring

• Virginia Knapper
• Charlene Napper
• Donald Taylor
• Paula Haskins Williams