Few mountain passes in the Appalachian Mountains of the Eastern United States are as well known and historically significant than Cumberland Gap that sits on the Virginia-Kentucky state line (and just north of Tennessee, too). This mountain gap was named for the unfortunate character, Prince William, Duke of Cumberland (1721-1765), son of King George II and victor over Bonnie Prince Charlies at the 1746AD Battle of Culloden. Two counties in Virginia alone are also named for him: Prince William County, while he was but a boy in 1731AD, and Cumberland County in 1749AD, after his victory at Culloden.
This Gap, which is a low point in the Cumberland Mountain of the Appalachians, was once the gateway to the Ohio Valley and what is now Kentucky. Indeed, Daniel Boone cut his Wilderness Road through this Gap in the mountains. He was hired to clear this path to open up the settlement of Kentucky in 1775AD.
The next year, 1776AD, the Virginia Assembly formed "Kentucky County" to administor these newly settled lands. That rather massive Virginia county would be split into three counties (Fayette, Jefferson, and Lincoln) in 1780, follwed by six other new counties before the whole area acheived statehood as Kentucky in 1792AD. Just so you know, one of those six others, Bourbon County, formed in 1785, was named for the French Royal family that assisted the cause of American Independence, and gave its name to the famous corn-based whiskey that is one of the glories of the Commonwealth of Kentucky.
A Map of the Wilderness Road and the 18th century frontier of Virginia (Recall that Kentucky remained a part of Virginia until its statehood in 1792) Cumberland Gap marks the point where the Wilderness Road enters the Appalachian Plateau.
The Cumberland Gap proved a point of strategic interest during the American Civil War, as well, changing hands several times.
While formerly used for US Highway traffic, a tunnel has now been constructed allowing the Cumberland Gap to rest as a historic park.
Today the Gap sits at the heart of a National Park Service installation: Cumberland Gap National Historical Park:
This National Park Service map affords an excellent idea of what is at the Gap today: