US-421 is a spur of US-21 and runs 941 miles. A third of it runs across the state og North Carolina, 328 miles.
Today, US-421 is aligned along the interstate bypass around Indianapolis, Indiana, but originally it ran right through the city. From the south, it entered on Southeast Avenue to downtown where it merged with US-40 (Washington Street) to West Street, Northwestern (now MLK Dr.) and Michigan Road.
Then it was on to Michigan City where it originally ended at US-12, near Lake Michigan. It now ends farther south at the intersection of US-20.
Some other cities the road passes through:
Kentucky-- Frankfort, Lexington and Richmond
Virginia and Tennessee-- Bristol
North Carolina-- Winston-Salem, Greensboro and Wilmington
All the Way on 421. --RoadDog