Since its creation in 1878 Idlewild has been a place for families to enjoy. The property was owned by William Darlington who gave Judge Thomas Mellon, the owner of the Ligonier Valley Railroad, the right to use the property for a park. Originally designated as a leisure and picnic area built on both sides of the railroad, the park included campgrounds, a man-made lake, picnic tables, and a large hall.
By the 1930s, although enjoyed by some, the park had not fully become popular. Judge Mellon's son, Richard B. Mellon sought to remedy that. The park was given a makeover and numerous pavilions, bandstands, rides, and lunchrooms were added.
By the 1950s the park was a success. In 1951 the owners of the land, the Macdonald family, who has also been managing the park for years, bought the park from the Mellon family. The railroad closed in 1952 but did not stop vacationing families from visiting. Storybook Forest was added in 1956 and quickly became an iconic favorite of visitors.
In 1983 Idlewild was purchased by Kennywood Park Corporation. The 1980s saw new things for the park including Jumpin' Jungle, Hootin Holler, the H20hhh Zone, Mister Rodgers Neighborhood, and Racoon Lagoon. In the 1990s the park doubled in size by adding state of the art roller coasters and water slides, leading to a name change of Idlewild & Soakzone.
In 2012 Idlewild was recognized as a historical place and given a roadside marker. The park is the oldest theme park in Pennsylvania, the 3rd oldest park in the country, and the 12th oldest park in the world. Idlewild has seen generation after generation come through its whimsical gates and remains a wonderful park for small children and families today.