Route 175 begins at an off-ramp from New Jersey Route 29 and Aberfeldy Drive in the capital city of Trenton. Inside the city limits of Trenton, the route carries one-way traffic northbound and is maintained by the City of Trenton. The route heads northward, progressing through the northern residential districts on Sanhican Drive. The highway continues, paralleling Route 29 for a distance. At an intersection with Afton Avenue, the continuation of Abernethy Drive, Route 175 changes names from Sanhican Drive to River Road. The road becomes two-way, enters Ewing Township, and is maintained by the New Jersey Department of Transportation. The highway continues, intersecting with Mercer County Route 643 in Ewing. A short distance later, Routes 175 and 29 pass under the West Trenton Railroad Bridge, which carries CSX's Trenton Subdivision and SEPTA's West Trenton Line, and head along the Delaware River, passing to the south of several high-end mansions. Route 175 itself passes to the south of condominium complexes, intersecting with the access road shortly afterward. A short distance later, Route 175 juts to the northeast near a commercial business, interchanging with Route 29. After the short interchange, the highway continues along the side of Route 29, intersecting with Wilburtha Road in Ewing. Routes 175 and 29 continue northward, crossing through the woodlands north of Trenton, until Route 175 makes a bend to the northeast, intersecting with West Upper Ferry Road. The highway turns onto West Upper Ferry Road, heading to the northeast, crossing through a wealthy district in Ewing surrounded by woodlands. The route begins to enter fields, crossing over the Delaware and Raritan Canal on character-less bridge. After the bridge, Route 175 turns to the north onto River Road, while West Upper Ferry Road continues as Mercer County Route 634. Route 175 heads northward along the Delaware and Raritan Canal as River Road, passing through woodlands and residential homes. A short distance later, it intersects with State Police Drive, a road serving the New Jersey State Police headquarters. Continuing along the canal, Route 175 progresses northward, intersecting with Trooper Drive before crossing under Interstate 295 at Interchange 76. Route 175 continues for a short distance, becoming a divided highway just after the overpass. A short distance later, the highway comes to end as the right-of-way continues onto Route 29.
History
Route 175 is an original alignment of Route 29 through Trenton and Ewing designated in the 1927 renumbering of state highways in New Jersey. The original plan for a freeway along Route 29 started in the 1930s, with no progress until the 1950s, when construction began on John Fitch Parkway named after John Fitch. Construction of this alignment used up much of the available waterfront in Trenton, and by 1969, after Route 29 was realigned onto the new freeway, Route 175 was designated on the former alignment. Route 175 was designated as a No Passing Zone by NJDOT on September 14, 1982. The two highways have remained intact since.
