Milton State Park is an 82 acres (33 ha) Pennsylvania state park in Milton in Northumberland County, Pennsylvania in the United States. The park is on Montgomery Island in the West Branch Susquehanna River, just east of the village of West Milton in Union County. Milton State Park is on Pennsylvania Route 642.Milton State Park is within sight of downtown Milton, Pennsylvania. This does not mean that it lacks for natural beauty. The island is surrounded by the waters of the West Branch Susquehanna River and the southern part of the island is not developed. It is covered in a forest of river birch, silver maple and sycamore trees. Milton State Park is a haven for migrating birds and waterfowl.