 The freeway generally passes along the north and east edges of the Black Hills.The route then enters Pennington County, where it passes through the northern edge of Rapid City, gateway to the Black Hills and the nearest passing to Mount Rushmore National Memorial, as well as other scenic attractions including Custer State Park and the Needles Highway.Rapid City is also where the interstate has its westernmost auxiliary route, Interstate 190, which links the interstate to the western edge of the downtown area.