Harriet Tubman Underground Railroad National Historical Park is a 480-acre (190 ha) National Park Service unit in the U.S. state of Maryland. It commemorates the life of former enslaved Harriet Tubman, who became an activist in the Underground Railroad prior to the American Civil War. The Harriet Tubman Underground Railroad National Monument was created by President Barack Obama under the Antiquities Act on March 25, 2013. The portion of the monument administered by the National Park Service was later designated a National Historical Park in 2014, and the remainder is managed by the Fish and Wildlife Service as part of Blackwater National Wildlife Refuge.