 The freeway, first designated as US 48, was extended westward through the 1970s, reaching West Virginia in 1976.The portions of US 40 that were bypassed between Cumberland and Keysers Ridge became U.S. Route 40 Alternate, which first appeared on MDSHA maps in the early 1980s.At this time, US 40 was realigned to follow the US 48 freeway, sharing the freeway with US 48.