The presence of people at Rocky Glen has been documented to the late 19th Century. Although the unique box canyon and upland meadows would have been of interest to Native Americans, there is at present no evidence of their presence at Rocky Glen. Nearby Peoria was established in the 1670s composed of Native Americans, French voyageurs and African Americans.
Coal mining and recreation have occurred side by side at Rocky Glen as the chronology shows below. The first accidental miner death (which were frequent in the coal mines), is buried at nearby Pottstown Cemetery. The Vicary family-owned Rocky Glen and operated the large coal mine until the early 1920s. The mine entrance is made of reinforced concrete and had narrow gauge railroad ties for coal cars. The surrounding area around the horizontal mine shaft is deeply covered in tailings, the unusable portion of coal that was hand sorted (usually by women and children), from the coal and discarded. The mine entrance is visible within Rocky Glen, south of the main trail and marked with an informational sign.