The Cumberland Gap is a natural land formation passing through the long ridge of the Cumberland Mountains (part of the Appalachian Mountains). It crosses through portions of Kentucky, Tennessee, and Virginia. For hundreds of years it served as an important passageway through that portion of the Appalachians, and was considered the "First Doorway to the West". The gap is contained within the modern Cumberland Gap National Historical Park, a natural break in the Appalachian Mountains.
Covering some 32 square miles, the park draws nearly a million tourists per year, and offers an interactive museum with exhibits highlighting the area's cultural and natural significance.
On April 11, 2016, the city of Middlesboro, Kentucky offered a pictorial postmark bearing the image of a buck and a stylized National Parks Service emblem, to commemorate the launch of the new Cumberland Gap United States quarter.
These four maximum cards were created from a vintage "postcard book" originally purchased at the park's gift shop, which I purchased on eBay and cut apart.