Best known for its pivotal role in opening up the western frontier and its association with explorers and pioneers, the legendary Cumberland Gap has long been celebrated in music and literature. To better preserve that history, Cumberland Gap National Historical Park was authorized in 1940 and now covers more than 24,000 acres in Kentucky, Virginia, and Tennessee. Daniel Boone is remembered here, as well the Native Americans who used the path through the mountains for trade and warfare, the Civil War soldiers who took turns guarding this strategic portal, the geologists and industrialists who...