Maryland Route 77 is a state highway in the U.S. state of Maryland. The state highway runs 20.74 miles (33.38 km) from MD 64 in Smithsburg east to MD 194 in Keymar. MD 77 is the main east–west highway of northern Frederick County. The state highway connects Thurmont with eastern Washington County via Foxville, which lies between South Mountain and Catoctin Mountain near Catoctin Mountain Park and Cunningham Falls State Park. MD 77 links Thurmont with western Carroll County through the communities of Graceham, Rocky Ridge, and Detour in the Monocacy River valley. MD 77 was constructed from Thurmont east to Detour in the 1920s and early 1930s. A disjoint section of MD 77 was built between Cavetown and Foxville in the late 1930s. The portions of the modern highway between Foxville and Thurmont and from Detour to Keymar were county highways until they were designated part of MD 77 in 1956. MD 77's western terminus was moved east to MD 64 in Smithsburg in 1960.

Maryland Route 64 is a state highway in the U.S. state of Maryland. The state highway runs 13.33 miles (21.45 km) from U.S. Route 40 in Hagerstown east to the Pennsylvania state line near Ringgold, where the highway continues north as Pennsylvania Route 997. MD 64 is an L-shaped route in northeastern Washington County, connecting Hagerstown with Smithsburg, Cavetown, and Chewsville and Smithsburg with Ringgold and Waynesboro, Pennsylvania. The state highway is maintained by the Maryland State Highway Administration except for the municipally-maintained portion within the city limits of Hagerstown. MD 64 was once a turnpike between Hagerstown and Smithsburg. The state highway was constructed from Smithsburg to the Pennsylvania state line in the mid 1910s and from Hagerstown to Smithsburg in the early 1920s. MD 64 was reconstructed in its entirety in the 1950s, resulting in bypasses of all four communities east of Hagerstown the highway serves.