SR 9 is the main east–west highway of northwestern Loudoun County, connecting Leesburg with Hillsboro and the West Virginia cities of Charles Town and Martinsburg. As a result, the state highway and its West Virginia continuation are a major, overburdened commuter route between the Eastern Panhandle of West Virginia and Washington, D.C.
SR 9 is a significant east-west highway in Loudoun County, serving as a crucial link between Leesburg, Hillsboro, Charles Town, and Martinsburg. Its heavy traffic volume makes it a major commuter route connecting the Eastern Panhandle of West Virginia to Washington D.C.