 MD 117 east of MD 124 was originally part of the latter highway, which was constructed in the early 1910s.The two gaps in MD 117 were filled in the early to mid-1950s before the route between Boyds and Gaithersburg was transferred to county maintenance in the late 1950s.MD 117 was returned to its course from Boyds to Gaithersburg in the mid-1970s and extended to downtown Gaithersburg over what had been MD 124 in the 1980s.