Designated a National Historic Civil Engineering Landmark in 1970, this tunnel is the oldest existing transportation tunnel in the United States. At the time of its construction it was considered a work almost unknown in this country.
Dug through the ridge dividing the waters of the Quittapahilla Creek and Clark's Run, the tunnel was originally 720 feet long. Drilling was done by hand and blasting with gunpowder through Argillaceous Slate Rock with veins of hard flinty limestone 80 feet below the summit of the ridge. Progress of the work was 5 yards lineal per week.
Work began May, 1825, and was completed in June, 1827, at a total cost of $30,464.29. The tunnel's length was reduced to 600 feet during the canal enlargement in 1858 at a cost of $8280.
Simeon Guilford was the engineer in charge with John B. Ives as contractor. The first boat to pass through the tunnel was the Alpha of Tulpehocken on June 12, 1827. Boats were poled through the tunnel against the ceiling while mules were led over the top of the ridge.