Many changes occurred between 1900 and 1930. In the early 1910's, Kennywood built two large roller coasters: The Racer and the Speed-O-Plane. Important rides added in the 1920's were three coasters: Jack Rabbit (Designed by Miller and Baker in 1920), Pippin (designed by John Miller in 1924), and Racer in 1927 replacing the old Racer built in 1910. The park added a huge swimming pool in 1925.
The Great Depression from 1930 to 1935 was especially hard on the park. Dancing helped keep the park in business during this period as great dance bands played in the park from 1930 to 1950. Kennywood prospered in the second half of the 1930's as new rides including Noah's Ark (1936) were added. During the Second World War period, the park couldn't add new rides, but it did buy a used ferris wheel and a miniature train. It still operates the latter.
In the 1950's school picnics grew by leaps and bounds. The park added many new rides to Kiddieland. Some popular rides in this period included the Hurricane, the Looper, the Rotor (the first ride imported from Europe), the Wild Mouse and the Octopus. With the 1960's and 1970's came competition from "
Disneyland" and other theme parks. Kennywood decided to spend the money necessary to remain competitive. The Turnpike was built in 1966 followed in 1968 by the Thunderbolt, which was redesigned from the Pippin by resident coaster whiz, Andy Vettel. With the Thunderbolt came the designation "The Roller Coaster Capital of the World." The Dance Pavilion, a dark ride since the 1950's, burned in 1975.