I-70 meets US 40 (National Pike) at a cloverleaf interchange as the two highways leave the suburban area surrounding Hagerstown. The Interstate curves to the southeast and has a diamond interchange with MD 66 (Mapleville Road) near Beaver Creek. I-70 crosses Beaver Creek and Black Rock Creek and gains an eastbound climbing lane as the highway ascends South Mountain and passes through Greenbrier State Park. At the top of the mountain, the Interstate passes under US 40 and the Appalachian Trail and enters Frederick County. I-70 has a pair of rest areas on the east side of the mountain, one per direction. The westbound rest area is where the Beltway snipers, John Allen Muhammad and Lee Boyd Malvo, were apprehended by police in October 2002.