New Jersey Route 303

Route 303
Route information
Maintained by NJDOT
Existed	1938–1950s (never built)
Major junctions
South end	Route 4 in Teaneck
North end	NY 303 in Northvale
Location
Country	United States
State	New Jersey
Counties	Bergen
Highway system
New Jersey State Highway Routes Interstate US State Scenic Byways
← Route 300 → US 322

Route 303 was a proposed state highway in the northeastern portion of New Jersey. The route originally was defined to go from an intersection with current-day Route 4 in Teaneck, then progressing northward through several local communities before connecting to the New York state line at Northvale. At the state line, Route 303 was to intertwine and become the current-day New York State Route 303 (NY 303). The alignment runs along the current alignment of County Route 505, which becomes NY 303 at the state line.

It was first planned in 1938 as Route S4D (a spur of Route 4), and once the 1953 renumbering of highways occurred, the S-4-D designation was replaced by Route 303. However, the highway was never assigned and remains unused to this day.