Susquehanna State Park occupies a broad stretch of the lower Susquehanna River north of Havre de Grace, with lands on both banks and on river islands. Shaped through a 1958 land donation by J. Gilman D’Arcy Paul and state acquisitions beginning in 1960, it unites scenic river landscapes with historic sites tied to the Susquehanna corridor. The Rock Run Historical Area includes the Rock Run Grist Mill, the 1804 Carter-Archer Mansion, canal remains, and the restored Jersey Toll House, while the Steppingstone Museum preserves Harford County rural arts and crafts from about 1880 to 1920. Trails, fishing, boating, camping, hiking, picnicking, and equestrian use remain central to its role.