| Province: | NB |
| Type: | NB |
| Route: | 3 |
| Length Km: | 91.5 |
| Maint: | New Brunswick Department of Transportation |
| Length Ref: | [1] |
| Length Round: | 1 |
| Established: | 1927 |
| Direction A: | South |
| Direction B: | North |
| Terminus A: | near St. Stephen |
| Junction: | near McAdam |
| Terminus B: | near Longs Creek |
| Previous Type: | TCH |
| Previous Route: | 2 |
| Next Type: | Route |
| Next Route: | 4 |
Route 3 is 92 kilometres long and goes from Route 170 in St. Stephen to Route 2 (the Trans-Canada Highway) at Longs Creek, near Fredericton.
From St. Stephen, Route 3 goes north along the west bank of Dennis Stream, through the community of Moores Mills. The road turns northeast through Lawrence Station and mostly uninhabited land to meet Route 4 near York Mills. From there, Route 3 continues in a northeasterly direction through Harvey Station, then turns north to the Trans-Canada Highway at Longs Creek.
There have been no major changes or realignments to Route 3 since the 1950s.