U.S. Route 340 (US 340) is a spur route of US 40, and runs from Greenville, Virginia to Frederick, Maryland. In Virginia, it runs north–south, parallel and east of US 11, from US 11 north of Greenville via Waynesboro, Grottoes, Elkton, Luray, Front Royal, and Berryville to the West Virginia state line. A short separate piece crosses northern Loudoun County on its way from West Virginia to Maryland.