 US 11 is the descendant of a trail blazed through the Great Appalachian Valley in the 18th century.In the 19th century, this trail was upgraded to a pair of turnpikes, one from Williamsport to Hagerstown and the second from Hagerstown to the Pennsylvania state line.The highway was constructed in its modern form in the early 20th century, with the bridge across the Potomac River constructed in 1909 and the old turnpikes paved as all-weather roads by the nascent Maryland State Roads Commission in the 1910s.