Maryland Route 108 (MD 108) is a state highway in the U.S. state of Maryland. The highway runs from MD 27 in Damascus to MD 175 in Columbia. MD 108 is an S-shaped highway that winds through the northern Montgomery County and central Howard County. The highway connects the Montgomery County communities of Laytonsville, Olney, Sandy Spring, and Ashton with the Howard County villages of Highland and Clarksville. MD 108 serves as the northern edge of Columbia and connects several of the planned community's suburban villages. MD 108 originally connected Damascus with Olney. This highway was constructed between the mid-1920s and early 1930s. MD 108 from Olney to Columbia, part of Clarksville Pike, was originally constructed as MD 28 from Olney to Ashton and the original MD 27—later U.S. Route 29 (US 29)—from Ashton to Columbia. The highway was constructed near Columbia in the mid-1910s and from there to Olney in the late 1910s. MD 108 east of US 29 originally consisted of a county road and MD 531, which was built in the early 1930s and later became MD 175. MD 108 was extended east from Olney to Ashton in the mid-1940s and from Ashton to MD 175 in 1960 after US 29's present highway was built. The highway was extended to its present eastern terminus in the mid-1970s. MD 108 was expanded to a divided highway in Columbia in the late 1980s and in Olney in the mid-1990s. Route description MD 108 begins at a three-way intersection with MD 27 (Ridge Road) in the center of Damascus. The latter highway heads north and west from the intersection; MD 108 heads east as four-lane undivided Main Street. The street reduces to two lanes just east of Woodfield Road, which heads south as MD 124. MD 108's name changes to Damascus Road at Howard Chapel Road at the east end of the village. The highway heads southeast and meets the southern end of Annapolis Rock Road, which leads to MD 94 at the Montgomery–Howard county line. MD 108 meets the northern end of MD 650 (Damascus Road) in the hamlet of Etchison, where the highway turns south onto Laytonsville Road. The route intersects Brink Road and Sundown Road next to the Layton House in the center of the town of Laytonsville. MD 108 veers southeast out of Laytonsville and continues along Laytonsville Olney Road. The highway passes a pair of