White Clay Creek Preserve is a 3,050-acre Pennsylvania state park north of Newark, Delaware, set aside to limit development and protect both natural habitats and historic landscapes. Donated by the DuPont Company in 1984, it preserves a valley with a long human past, including the Native town of Opasiskunk, associated with Lenape chief Kekelappen and occupied from the Archaic Period into the early 18th century. Nearby stand reminders of early Pennsylvania, including the Yeatman Mill House site and the 1729 London Tract Baptist Meetinghouse. The preserve also reaches the Mason-Dixon Line and Twelve-Mile Circle, where colonial boundary markers survive, and it has expanded through the Big Elk Creek Section.