Hanging Rock (Upper Merion Township, Pennsylvania)

Hanging Rock, also known as Overhanging Rock, or locally as Drummond's head, is a historic natural feature which is located in Gulph Mills, Upper Merion Township, Montgomery County, Pennsylvania. It is a large natural outcropping of phyllite that protrudes approximately eight feet over a roadway, Pennsylvania Route 320 (South Gulph Road), which was laid out as a public highway between 1711 and 1712.

It was listed on the National Register of Historic Places in 1997.

History and geographical features
The road near Hanging Rock, Pennsylvania Route 320 (South Gulph Road), was built between 1711 and 1712 to serve as a public highway. It was subsequently used by General George Washington and the Continental Army to move troops into Valley Forge for the winter encampment of 1777–1778.

The rock formation was dedicated as a memorial to that march by the Valley Forge Historical Society in 1924.

In 1917 and 1954, holes were drilled into Hanging Rock for the placement of dynamite in an effort to remove the rock. This, along with erosion and vehicle collisions, has changed the shape of the rock over time. The "overhang" of the rock has decreased since the invention of the automobile as car crashes have chipped away at the rock over the years.

In January 2020, PennDot started a project to realign Route 320 (South Gulph Road) away from Hanging Rock, which had protruded into the roadway, resulting in limited sight distances; the project was completed in June 2022.

Hanging Rock was listed on the National Register of Historic Places in 1997.