The first section of MD 23 to be paved was the part of the Old York Turnpike from MD 138 to MD 439, which was improved as a  macadam state-aid road by 1910. The portion of MD 23 from Hickory to Jarrettsville was designated one of the original state roads by the Maryland State Roads Commission in 1909.
The initial segment of MD 23 paved was the Old York Turnpike, between MD 138 and MD 439, which was upgraded as a macadam road by 1910. The portion of MD 23 from Hickory to Jarrettsville was designated one of the original state roads by the Maryland State Roads Commission in 1909.