Milton State Park is an 82-acre island on the West Branch Susquehanna River, between the Boroughs of Milton and West Milton. The northern half of the park has day use facilities and the southern half remains in a wooded state for hiking and nature study.

In 1762, Marcus Huling Jr. claimed the big island, which eventually came to be called Montgomery Island. Within a decade, he planted an apple orchard. At this time, this part of the state was claimed by Pennsylvania and Connecticut.

Eventually the land came to be controlled by the Straub Brothers, who in 1824 built a dam across part of the river and erected a sawmill and gristmill. The brothers won the contract to build a bridge across the river between the three islands.

The mills eventually became unprofitable and the island was only used as farmland. Floods continually washed away parts of the bridge, which were rebuilt. By the early 1900s, farming ceased and there were now two islands, one of the smaller islands having joined the big island, making it even larger. The island was subdivided to many owners and part became athletic fields. The Milton Rotary Club worked to consolidate the deeds to one title for the Borough of Milton, who then transferred the title to the Commonwealth of Pennsylvania in 1966.

The floodwaters of Hurricane Agnes completely covered the island in 1972. Federal relief money helped rebuild the facilities. In 1987, PA 624 was relocated across the island, providing a new boat launch and transferring the final piece of property to state park control.