Letchworth State Park, Castile NY. (Western New York) Not really along the PA border, about 40 miles north. It's a NY State Park, not a ACE Park.
Considered to be "The Grand Canyon of the East"
https://parks.ny.gov/parks/79/details.aspx
The Army Corps of Engineers built the Mount Morris Dam just east of the park, maybe that's what the fellow camper was referring to.
I am not aware of any campgrounds with a canyon view along the NY/PA border.