Almost every electric interurban railway line had a park along its lines that could only be reached by travelling on the trolley car. Idylwild Park was just such a park on the Galt, Preston & Hespeler Street Railway. Situated between Preston and Hespeler, Idylwild Park was filled with trees, had two spacious pavilions where dances and other events were held, a refreshment booth, swings, a baseball diamond, a water spring and lots of picnic area. The park, having the Speed River running through it, was also home to a large mosquito population prompting the nick-name, 'Mosquito Park'. Idylwild Park was closed in 1916.

This postcard view shows car 51, on the original right-of-way of the G.P.&H., approaching the park enroute to Preston from Hespeler. Much of the Hespeler Branch trackage was moved away from the river in 1918 to escape the problem of spring flooding. The Mill Run Trail now occupies the railway lands shown in this picture.