Maryland Route 6 is a state highway in the U.S. state of Maryland. The state highway runs 47.36 miles (76.22 km) from a dead end at the Potomac River in Riverside east to MD 235 in Oraville. MD 6 connects several small communities in southern Charles County and northern St. Mary's County with U.S. Route 301 in La Plata, the county seat of Charles County, and MD 5 in Charlotte Hall. The state highway also provides access to multiple historic sites around Port Tobacco, the original county seat of Charles County. MD 6 was one of the original highways numbered by the Maryland State Roads Commission in 1927. The state highway was constructed from La Plata to Riverside in the late 1910s and early 1920s. The La Plata–Charlotte Hall section of the highway was built in the mid-1920s. The portion of MD 6 east of Charlotte Hall was mostly built in the late 1920s and early 1930s. The final section of the state highway was completed in Oraville in 1940.

Maryland Route 235 (MD 235) is a state highway in the U.S. state of Maryland. Known as Three Notch Road, the state highway runs 30.63 miles (49.29 km) between its southern intersection with MD 5 in Ridge and its northern intersection with MD 5 near Mechanicsville. While the southern part of the state highway is a two-lane undivided rural road, the northern part of MD 235 is a four- to six-lane divided highway connecting Naval Air Station Patuxent River and the Washington, D.C., metro area in conjunction with MD 5. Three Notch Road has been the main highway between northern St. Mary's County and Point Lookout since the colonial era. The highway was reconstructed as the modern MD 235 between 1923 and 1938. The state highway was then completely rebuilt during World War II to serve the recently established NAS Patuxent River. Between 1960 and 1985, MD 235 was converted into a four-lane divided highway to the west and north of the military base. In the face of increasing activity at the base, the highway adjacent to NAS Patuxent River was expanded to six lanes in the early 2000s.