Originally US 301 was much shorter. Its former northern terminus was in Baltimore, Maryland. It followed the alignment of the current Maryland Route 3, portions of the Baltimore Beltway, and Maryland Route 648. Route 301 ended in Southwestern Baltimore on Monroe Street at the intersection with U.S. 1. (Later, Route 3 was supplanted north of Millersville by Interstate 97.) It was later extended into the state of Delaware, along a different alignment that bypassed Baltimore altogether. Until 2019, the northern terminus was at US 40 in Glasgow, Delaware, however a new tolled freeway was built by the state of Delaware to carry US 301, it currently terminates southeast of the former terminus, at Delaware Route 1 just south of the Chesapeake & Delaware Canal. The original southern end was in South Carolina, though it has been repeatedly extended south many times to US 41 in Sarasota, Florida.