Route 1 is a highway in the southern part of the Canadian province of New Brunswick. It begins in the west from the Canada–United States border at St. Stephen, and runs east for 239.11 kilometres (148.58 mi) to Route 2 at River Glade.

St. Stephen is a Canadian town in Charlotte County, New Brunswick, situated on the east bank of the St. Croix River around the intersection of New Brunswick Route 170 and the southern terminus of New Brunswick Route 3. The St. Croix River marks a section of the Canada–United States border, forming a natural border between Calais, Maine and St. Stephen. U.S. Route 1 parallels the St. Croix river for a few miles, and is accessed from St. Stephen by three cross-border bridges.