Ohio State Road has not had any significant changes since 1955, but it had been renamed from SR 194 in 1923, which was decommissioned in 1927, then SR 500 was commissioned in 1937 with some additional changes through 1955.
No significant changes have taken place to this state route since 1955. In 1923, SR 500 was signed as SR 194 northeast from Payne to Paulding and west of Payne was a county road. SR 194 was decommissioned in 1927 leaving the route that later became SR 500 as a county road. The commissioning of SR 500 took place in 1937, and replaced a county road west of Payne, while east of Payne it replaced the former route of SR 194. The highway had a gravel surface between the Indiana state line and SR 49, while between SR 49 and its eastern terminus at SR 111 it was paved. In 1951, the westernmost portion of SR 500 between the Indiana state line and SR 49 was paved. By 1955, SR 113, now SR 613, was rerouted to be concurrent with SR 500 northeast of Payne to the current eastern split of the two routes. 
