The park was brought up to its present size in 1981, when an additional were donated to the state by William Poole Bancroft's Woodlawn Trustees. Bancroft, a nationally recognized land conservationist with a deep appreciation for the beauty of the Brandywine, had become concerned about the expansion of nearby Wilmington and purchased a considerable amount of land in the Brandywine region with the intention of preserving it as open space parkland for future generations. He had also established the Trustees to continue acquiring land around the Brandywine after his death to be managed as parkland.