State Highways of New Jersey

The highway was originally legislated as NJ 30. Originally, NJ 29, which met NJ 30 at Ringoes after coming over from Lambertville, was supposed to continue east on Old York Road to Somerville, while NJ 30 was to head northeast to Flemington, where it would meet NJ 12. Soon, though, the state realized that it did not need two highways between Ringoes and Somerville, and so the plans were combined. NJ 29 and NJ 30 shared the road from Ringoes to Flemington, which became the east end of NJ 12, and NJ 29 continued over a new road to Somerville.

In 1953, New Jersey decided to eliminate duplicate designations with US highways. Since US 202 ran along NJ 29 from Lambertville to Somerville (and US 22 ran along NJ 29 from Somerville to Newark), NJ 29 was truncated to Lambertville. Separately, NJ 43, the White Horse Pike, was stripped of that number, and it became simply US 30. That meant NJ 30 had to be renumbered, and the State Highway Commission made it NJ 69. That proved to be a poor choice, as youthful motorists with a larcenous streak found those signs rather popular. In 1967, NJDOT subtracted 69 from 100 and found that 31 was an available number, so this highway became NJ 31. (The old NJ 31 had become part of US 206, and was designated 206 by the state in 1953.)

With US 202 being rerouted over a freeway extension from Ringoes to a toll bridge north of Lambertville, NJ 31 now joins the four-lane highway just south of Ringoes. A two-mile stretch of Old York Road east of Ringoes that used to be both NJ 29 and NJ 30 is now part of NJ 179, while the short stretch of old NJ 30 between the four-lane and Ringoes has reverted to Hunterdon County control, as part of SR 579.

Mile	Street Name	Feature
48.93	Northern terminus of , White Twp, Warren Co
48.93
48.88		Pequest River	bridge	Pequest River
48.34		White Twp, Warren Co Oxford Twp, Warren Co
46.85		Wall St		James Burns Dr
46.83		Furnace Brook	bridge	Furnace Brook
46.56		Academy St		Oxford Ave
46.14		Oxford Twp, Warren Co Washington Twp, Warren Co		Oxford Twp, Warren Co Mansfield Twp, Warren Co
45.83				Tunnel Hill Rd
45.76		Washington Twp, Warren Co Mansfield Twp, Warren Co
45.15		Mansfield Twp, Warren Co Washington Twp, Warren Co
44.47		Pohatcong Creek	bridge	Pohatcong Creek
44.35		Jackson Valley Rd		Jackson Valley Rd
43.55		Washington Twp, Warren Co Washington Boro, Warren Co
42.95		Abandoned railroad spur	underpass	Abandoned railroad spur
42.84		Washington Ave		Washington Ave
42.77		Shabbecong Creek	bridge	Shabbecong Creek
42.54		Railroad	underpass	Railroad
42.46		Washington Boro, Warren Co Washington Twp, Warren Co
42.23				Washburn Ave
41.70		Branch Musconetcong River	bridge	Branch Musconetcong River
41.15		Lincoln Ave
41.06		Branch Musconetcong River	bridge	Branch Musconetcong River
40.74		Bryants Rd
40.72		Branch Musconetcong River	bridge	Branch Musconetcong River
40.18		Asbury-Anderson Rd		Asbury-Anderson Rd
39.43		Washington Twp, Warren Co Hampton Boro, Hunterdon Co
39.43		Musconetcong River	bridge	Musconetcong River
39.30		Main St		River Rd
38.41		Railroad	overpass	Railroad
38.30		Hampton Boro, Hunterdon Co Glen Gardner Boro, Hunterdon Co
38.11		Main St		Main St
37.97		Alpaugh Brook	culvert	Alpaugh Brook
37.71		Glen Manor Dr		School St
37.37		Branch Spruce Run	culvert	Branch Spruce Run
37.14		Fountain Grove Rd		Sanatorium Rd
36.81		Glen Gardner Boro, Hunterdon Co Lebanon Twp, Hunterdon Co
36.81		Spruce Run	bridge	Spruce Run
35.74		Rocky Run	culvert	Rocky Run
35.23		Van Syckels Rd
35.06		Willoughby Brook	bridge	Willoughby Brook
34.88		Lebanon Twp, Hunterdon Co Clinton Twp, Hunterdon Co
34.07		Longwood Dr		West Main St
33.41		Halstead St		Shopping center entrance
33.20		Clinton Twp, Hunterdon Co Clinton Town, Hunterdon Co
32.68		Clinton Town, Hunterdon Co Clinton Twp, Hunterdon Co
32.43			underpass
31.89			overpass
31.62		Country Club Dr		Walnut Pond Dr
31.33				Allerton Rd
30.97		Regional Rd		Regional Rd
30.70		Cramers Creek	culvert	Cramers Creek
29.95		Allerton Creek	culvert	Allerton Creek
29.93		Allerton Rd		Allerton Rd
29.85		Allerton Creek	culvert	Allerton Creek
29.51				Molasses Hill Rd
28.81		Payne Rd		Payne Rd
28.06		Prescott Brook	bridge	Prescott Brook
27.86				Old Clinton Rd
27.30		Clinton Twp, Hunterdon Co Readington Twp, Hunterdon Co
27.18		Branch Prescott Brook	bridge	Branch Prescott Brook
27.12		Stanton Station Rd
25.45		Readington Twp, Hunterdon Co Raritan Twp, Hunterdon Co
25.45		South Branch Raritan River	bridge	South Branch Raritan River
25.38		Railroad	underpass	Railroad
24.73				Shopping center entrance
24.50		Assiscong Creek	bridge	Assiscong Creek
24.40		Sand Hill Rd		Bartles Corner Rd
24.24		Gauntt Pl
24.05		Wescott Dr		Shopping center entrance
23.95		Minneakong Creek	culvert	Minneakong Creek
23.43		Walter E Foran Blvd		Walter E Foran Blvd
23.40		Railroad	at grade	Railroad
23.14		Raritan Twp, Hunterdon Co Flemington Boro, Hunterdon Co
23.14		Bushkill Creek	bridge	Bushkill Creek
23.13		Main St		Flemington Junction Rd
22.94		Flemington Boro, Hunterdon Co Raritan Twp, Hunterdon Co
22.87		Highland Ave		School entrance
22.63		Branch Bushkill Creek	culvert	Branch Bushkill Creek
22.53		Black River & Western Railroad	underpass	Black River & Western Railroad
22.30		Raritan Twp, Hunterdon Co Flemington Boro, Hunterdon Co
22.21		Church St		Voorhees Corner Rd
22.02			circle
21.87			circle
21.73		Reaville Ave		Reaville Ave
21.65		Flemington Boro, Hunterdon Co Raritan Twp, Hunterdon Co
21.53				Commerce St
20.99		S Main St
20.91		First Neshanic River	bridge	First Neshanic River
20.58		U-turn ramps		U-turn ramps
20.45		Second Neshanic River	bridge	Second Neshanic River
20.02		Hampton Corner Rd
19.87		Third Neshanic River	bridge	Third Neshanic River
19.44		Copper Hill Rd
19.27				Heron Glen Rd
18.93		Everitt Rd		Everitt Rd connector
18.14				Cornet Way
17.69		Raritan Twp, Hunterdon Co East Amwell Twp, Hunterdon Co
17.46		Old York Rd		Old York Rd
16.57		Wertsville Rd		Wertsville Rd
16.36			merge
16.32		Back Brook	culvert	Back Brook
16.19		Linvale-Harbourton Rd
16.15		Branch Back Brook	culvert	Branch Back Brook
16.07		East Amwell Twp, Hunterdon Co West Amwell Twp, Hunterdon Co
15.30		West Amwell Twp, Hunterdon Co East Amwell Twp, Hunterdon Co
14.82		East Amwell Twp, Hunterdon Co West Amwell Twp, Hunterdon Co
14.19		Branch Stony Brook	culvert	Branch Stony Brook
13.97		Harbourton Rd
13.38		West Amwell Twp, Hunterdon Co East Amwell Twp, Hunterdon Co
13.33		Peters Brook	bridge	Peters Brook
12.68		Branch Stony Brook	culvert	Branch Stony Brook
12.27		East Amwell Twp, Hunterdon Co Hopewell Twp, Mercer Co
12.27		Lambertville-Hopewell Rd		Lambertville-Hopewell Rd
12.21		Woodsville Brook	culvert	Woodsville Brook
11.78		Stony Brook	culvert	Stony Brook
10.19		Woodsville Rd		Woodsville Rd
9.91		Branch Stony Brook	bridge	Branch Stony Brook
9.66				Pennington-Hopewell Rd
9.41		Abandoned railroad	underpass	Abandoned railroad
9.20				Titus Mill Rd
8.36		Tree farm entrance		Main St
8.14		Hopewell Twp, Mercer Co Pennington Boro, Mercer Co
7.70		Pennington-Titusville Rd		Delaware Ave
7.65		Pennington Boro, Mercer Co Hopewell Twp, Mercer Co
7.29		Seminary Creek	culvert	Seminary Creek
7.02		Hopewell Twp, Mercer Co Pennington Boro, Mercer Co
7.02		Railroad	overpass	Railroad
6.95		Pennington Boro, Mercer Co Hopewell Twp, Mercer Co
6.77		Hopewell Twp, Mercer Co Pennington Boro, Mercer Co
6.73		Pennington Boro, Mercer Co Hopewell Twp, Mercer Co
6.31		Ingleside Ave		Ingleside Ave
6.09		Washington Crossing Rd	circle	Main St Washington Crossing Rd
5.48	Pennington Rd	Denow Rd		Denow Rd
4.95	Pennington Rd			Ramp from south
4.84	Pennington Rd	Delaware Expwy	overpass	Delaware Expwy
4.72	Pennington Rd	Ramp from south		Bull Run Rd
4.72	Pennington Rd	Hopewell Twp, Mercer Co Ewing Twp, Mercer Co
4.40	Pennington Rd	Charles Ewing Dr		Rockleigh Dr E
3.81	Pennington Rd	Upper Ferry Rd		Ewingville Rd
3.39	Pennington Rd	Carlton Ave		The College of New Jersey
2.80	Pennington Rd			Green Ln
2.43	Pennington Rd			Somerset St
2.35	Pennington Rd	Central Ave
1.79	Pennington Rd	Olden Ave		Olden Ave
1.51	Pennington Rd	Parkside Ave		Parkside Ave
1.15	Pennington Rd	Ewing Twp, Mercer Co Trenton City, Mercer Co
1.15	Pennington Rd	Parkway Ave		Parkway Ave
1.15	Pennington Rd	NJDOT jurisdiction City of Trenton jurisdiction
0.73	Pennington Rd	Prospect St		Prospect St
0.28	Pennington Rd	Calhoun St		Calhoun St
0.17	Pennington Rd	Willow St		Willow St
0.03	Pennington Rd	south		south
0.00	Pennington Rd	North Broad St		North Broad St
0.00	Southern terminus of , Trenton City, Mercer Co