US 9 Truck/DE 404 Truck split from US 113 by heading east-northeast on two-lane undivided Arrow Safety Road.

The road passes through a mix of farmland and woodland with some development, coming to a roundabout with South Bedford Street, where the name changes to Park Avenue.

The routes continue east before curving to the northeast, crossing the Delmarva Central Railroad's Indian River Subdivision line at-grade.

The road turns east and passes to the south of Delaware Coastal Airport, where it makes a curve to the north.

[2][3] The Delaware Department of Transportation (DelDOT) moved US 9 Truck to a new alignment of Park Avenue located further to the south.

[8] A ribbon-cutting ceremony was held on June 7, 2024, with DelDOT secretary Nicole Majeski and state and local officials in attendance.

The business route runs through commercial areas to the southeast of a residential development, gaining a center left-turn lane.

The road continues past homes and some businesses as it enters Lewes, where it crosses the Georgetown–Lewes Trail.

crosses the Lewes and Rehoboth Canal on a drawbridge and runs past businesses to the northwest and marshland to the southeast.

The route headed east from US 9 in Upper Township on County Route 623 (CR 623) before heading north on the Garden State Parkway and crossing the Great Egg Harbor Bay on the Great Egg Harbor Bridge, ending at an interchange with US 9 in Somers Point.

The designation was replaced by US 9[failed verification] following the demolition of the bridge in 2013, making it so that US 9 cloud be driven from its entirety once again.

It was created in 1954 after US 9 was rerouted to use the Garden State Parkway through the Toms River area but was later renumbered to Route 166.