With more historic structures than any other unit in the National Park Service, the C&O Canal National Historical Park documents and preserves over 200 years of America’s history. The major sites, like Great Falls Tavern and the Paw Paw Tunnel, get most of the attention from visitors. However, many structures in the Park have a hidden history that is not apparent at first glance. Go hunting for these gems!
Explore by region of the Park: East | Central | West
You can also copy this itinerary into our C&O Canal Itinerary Builder here.
East: DC to Brunswick
Mile Marker 0.0 Mile Marker 0.0/Tide Lock The Georgetown Tide Lock is the zero milestone terminus on the C&O Canal, and all measurements on the canal were calculated from this point; however, the construction of the canal did not begin here. Mile Marker 1.0 Alexandria Aqueduct One lone pier, the remainder of the north abutment above the Key Bridge, is all that stands of the once magnificent Alexandria Aqueduct. Also known as the Potomac Aqueduct, it was built between 1833 and 1843, and stood as a technological marvel of early 19th century engineering. Its purpose was to connect the C&O Canal to Alexandria via a seven-mile-long canal for trade and commerce. When the Civil War began, the federal government seized the aqueduct, drained the water, and converted it into a roadway to transport troops and supplies. After the war, it was converted back into an aqueduct with a toll bridge above. By the 1880s, the aqueduct was no longer in use. The wooden aqueduct was removed, and it was replaced with a steel truss structure that could carry heavier traffic to Virginia. When the Francis Scott Key Bridge was finished in 1923, the aqueduct was abandoned. Mile Marker 2.3 Incline Plane The Incline Plane was built in 1876 as a way to combat early traffic issues during the heyday of the canal. It lowered boats directly into the Potomac River to avoid boat traffic in Georgetown and delays there. Prior to that, some frustrated boat captains were having to wait two days to get into Georgetown from two miles away because of boat traffic. Since Georgetown was not the final destination for every boat and many just needed to go through Georgetown to access the Potomac River at the tide lock, the incline plane was created to enable boats to bypass Georgetown. A river lock wouldn’t work because the location where the backup occurred was more than 39 feet above the river at low tide. The Potomac Lock and Dock Company proposed the incline plane, which was a caisson into which a boat would float. The boat, encased in the caisson, traveled on the rails of the incline plane from the canal and descended into the river. It was balanced by two counterweights and powered by a turbine supplied with waterpower from the canal. This engineering marvel was the largest of its kind in the world. Unfortunately, it soon became non-essential as transportation on the canal dramatically declined in the following decade. The incline plane was seriously damaged during a flood in 1889 and was never put back into service. Today you can barely make out the incline straight up from the wayside exhibit along the canal. Mile Marker 13.8 Stop Gate Stop gates were constructed along the C&O Canal to protect the canal, its structures, and communities built around the canal from flood waters. This stop gate was originally built in 1852 and reconstructed with a modern winch system by the National Park Service in 2009. Located not far from the Great Falls Visitor Center, the top portion of the stop gate resembles a covered bridge but it’s actually a winch house. It stores a winch and planks of wood, just a little wider than the foundation. When the river floods, the stop gate is deployed to create a temporary dam that protects the canal downstream. The winch is used to lower the planks, one at a time, through the floor and into grooves that have been cut into both sides of the stone foundation. Some water does pass through, but the majority is stopped from rushing downstream into the canal and causing damage. The use of seven stop gates reduced flood damage and prevented additional devastation throughout the canal’s history.
Mile Marker 14.4
Washington Aqueduct
Every day, more than 150 million gallons of water from the Potomac River detours into the Washington Aqueduct system to serve the water needs of the nation’s capital. George Washington devised the plan for this system in 1798, but no one took the project seriously for another 50 years. The aqueduct was built in 1859 by the Army Corps of Engineers and in 1864, water from the Potomac finally began making its 12-mile, mostly underground trip to the Georgetown Reservoir. The gatehouse for the original intake system, built from distinctive red Seneca sandstone, still stands next to the Great Falls Tavern.
Mile Marker 22.8
Seneca Stonecutting Mill
The Seneca Stone Cutting Mill was the center of one of the industries associated with the canal. It operated from 1837 to the early 1900s, milling stone from Seneca Quarry for many structures on the canal and public buildings in Washington, D.C., including the iconic Smithsonian castle on the National Mall. The mill’s water wheel, and later a turbine, were powered by water from the canal. The Seneca Stone Cutting Mill also cut granite and stone shipped from neighboring quarries. Granite and marble used in the U.S. Capitol and the Washington Monument were cut here. In 1901, the mill closed its doors for the final time, and in 1972, the state acquired the land and it became a part of Seneca Creek State Park. Today, the mill ruins are all that remain.
Mile Marker 30.9
Ruins of Jarboe’s Store
Close to Lock 25 are the brick ruins of Jarboe’s store. During the late 19th century and early 20th century, Eugene E. Jarboe ran a grocery and feed store, while also serving as postmaster at Edward’s Ferry. Gene’s sons, Sam and John, ran the store after their father tragically drowned in the lock while loading cattle. The store closed in 1906, and the NPS re-stabilized the ruins from 2008-2010.