 In 1932, the route was slightly extended south to Convoy south of US 30 before absorbing SR 51 south to Greenville the next year.All of SR 51 was then renumbered to SR 49 in 1935 extending the route from downtown Dayton to Michigan.No major changes would occur to the routing until around 1960 when a part of SR 49 was rerouted on a new expressway segment of US 40 south and west of Clayton (now partly I-70) and the route through southern Darke County was straightened to bypass Arcanum.