Interstate 68, the National Freeway, runs along the historic National Road for much of its 80 miles in Maryland. From Morgantown, West Virginia, I-68 runs through Garrett, Allegany and western Washington counties in the high mountains of Maryland's far west, via Grantsville, Frostburg, Cumberland and ending in Hancock at Interstate 70, which continues eastward for another 90-plus miles toward Baltimore. As is the case with the state's segment of I-70, most of Maryland's portion of I-68 overlaps with U.S. Route 40, whose former surface alignment along the corridor now carries alternate and scenic route designations. Overlaps with U.S. routes 219 and 220 also exist in Garrett County and through downtown Cumberland. I-68 also passes near the Green Ridge State Forest and through a cut in Sideling Hill at which rest areas also serve each carriageway.