Provincial Trunk Highway 3 (PTH 3) is a provincial highway in the Canadian province of Manitoba. It runs from the Saskatchewan boundary (where it meets Highway 18) to the west limit of the city of Winnipeg (Formerly to Pembina Highway before the City Route System). It passes through major centres such as Morden, Winkler, and smaller communities such as Manitou, Darlingford, and La Rivière. It has been designated as the Boundary Commission Trail commemorating the historic red river cart trail which connected western communities to the Rocky Mountains of British Columbia.