 In 1937, CR 25, along with SR 540 between CR 25 and downtown Bellfontaine, was a part of SR 32, which would become US 33 one year later.By 1964, US 33 was routed onto its current alignment around the east side of Bellefontaine.Consequently, the former portion of US 33 from the previous western terminus of SR 540 west into downtown Bellefontaine became a westward extension of SR 540 which resulted in the highway taking on its present shape.