Route 54 runs 41.84 mi (67.33 km) from MD 313 in Mardela Springs, Maryland, east to DE 1 in Fenwick Island, Delaware.

The Maryland State Roads Commission (now MDSHA) immediately reciprocated by designating its portions MD 54.

Improvements have been made to the route west of Fenwick Island, including building a causeway to reduce flooding and adding a center left-turn lane.

Route 54 begins at an intersection with MD 313 in the town of Mardela Springs in Wicomico County, Maryland.

[1][5] Route 54 heads east as two-lane undivided Delmar Road, passing south of Mardela Middle and High School.

[5] After passing the stone marker indicating the intersection of the Transpeninsular Line with the southern end of the Mason–Dixon Line, the highway enters the southwest corner of Sussex County, Delaware, where it intersects Columbia Road at Packing House Corner.

[1][2][5] Route 54 continues east until Old Racetrack Road, where the highway turns southeast toward the state line.

After crossing the swamp, the highway intersects US 113 (Dupont Boulevard) on the west edge of the town of Selbyville.

[5] Route 54 continues east into Selbyville as Cemetery Road and crosses the Snow Hill Line of the Maryland and Delaware Railroad at-grade.

After passing to the north of the Fenwick Island Light, Route 54 reaches its eastern terminus at DE 1 (Coastal Highway) in Fenwick Island, one block west of the Atlantic Ocean and one block north of the town of Ocean City on the other side of the state line.

[16] By 1942, the remainder of the road in Delaware between the Maryland border and south of Columbia and Gumboro and Selbyville were paved.

[23] In September 2001, construction began to build an elevated causeway for Route 54 to the west of Fenwick Island in order to prevent flooding from high tides and storms.

The project involved building the new causeway to the north of the original alignment, using pre-cast concrete segments.

[24] In 2010, a $10 million project began to add a center left-turn lane along with bike lanes and sidewalks to the portion of Route 54 between DE 20 and Mallard Lakes, a section of road that was targeted for safety improvements due to rapid development; this project was completed in 2012.

The alternate route heads northeast from DE 54 on two-lane undivided Johnson Road, passing through a mix of farmland and woodland and crossing Dirickson Creek.

turns east onto Kent Avenue and crosses the Assawoman Canal, where it curves north and passes residential development before ending at DE 26 at Bethany Beach.