Known for most of its length as Crown Stone Road, the state highway runs 2.21 miles (3.56 km) from the Delaware state line in Marydel, where the highway continues east as Delaware Route 8 (DE 8), north to MD 302 in Templeville.

MD 454 begins at the Delaware state line in the town of Marydel in Caroline County, adjacent to a five-mile (8 km) Mason–Dixon marker that gives the highway its name.

[2] The highway continues east as DE 8 (Halltown Road) toward Dover.

The route immediately encounters the eastern end of MD 821 (Main Street) and crosses an unused railroad grade owned by the Maryland Department of Transportation.

The state highway turns north through farmland before entering the town of Templeville and terminating at MD 302 (Barclay Road), which forms the border between Caroline County and Queen Anne's County.