Kennywood is now the only park in the United States with three coaster landmarks.
The Thunderbolt is a wooden coaster that's unusual that the lift hill isn't immediately out of the station but is in the middle of the ride.
ACE was founded in 1978 has honored 30 coaster landmarks nationwide since 2002.
Kennywood's Jack Rabbit and Racer roller coasters were previously honored as landmarks by the group. All three are traditional roller coasters with wooden frames and tracks.
The Thunderbolt grew out of a former roller coaster known as the Pippin. The Pippin was built in 1924 and was expanded and rebuilt to become the Thunderbolt in 1968.
The Jack Rabbit was built in 1920 and the Racer in 1927.
Kennywood is located in West Mifflin, Allegheny County, about 15 miles west of Pittsburgh.