County Route 523 is a county highway in the U.S. state of New Jersey. The highway extends 29.55 miles (47.56 km) from Route 29 in Stockton to U.S. Route 202 (US 202) in Bedminster Township.

Route 29 is a state highway in the U.S. state of New Jersey. Signed north-south, it runs 34.76 mi (55.94 km) from an interchange with Interstate 295 (I-295) in Hamilton Township in Mercer County, where the road continues east as I-195, northwest to Route 12 in Frenchtown, Hunterdon County. Between the southern terminus and I-295 in Ewing Township, the route is a mix of freeway and expressway that runs along the Delaware River through Trenton. This section includes a truck-restricted tunnel that was built along the river near historic houses and Riverview Cemetery. North of I-295, Route 29 turns into a scenic and mostly two-lane highway. North of the South Trenton Tunnel, it is designated the Delaware River Scenic Byway, a New Jersey Scenic Byway and National Scenic Byway, that follows the Delaware River in mostly rural sections of Mercer County and Hunterdon County. The obsolete Delaware & Raritan Canal usually stands between the river and the highway. Most sections of this portion of Route 29 are completely shaded due to the tree canopy. Route 29 also has a spur, Route 129, which connects Route 29 to U.S. Route 1 (US 1) in Trenton.