US 15 was established partially along what had been a pair of turnpikes. The Frederick and Emmitsburg Turnpike connected Emmitsburg with Harmony Grove which was located at the northern end of Market Street at MD 26 on the north side of Frederick. The Frederick and Buckeystown Turnpike ran from its co-terminus with the Frederick and Monocacy Turnpike at Evergreen Point at what is today the junction of MD 85 and MD 355, south to south of Buckeystown. When the Maryland State Roads Commission (MDSRC) designated highways to be improved as part of a state road system in 1909, the Frederick–Emmitsburg highway was included in the new system. MDSRC originally planned to build the state road north from the city of Frederick along the Frederick and Turnpike, then turn east along Hayward Road to meet the Frederick and Emmitsburg Turnpike at Harmony Grove.