The name dates from the time of the Fraser Canyon Gold Rush (1858–1861). A "bar" is a gold-bearing sandbar or sandy riverbank, and the one slightly down river and opposite today's town was populated heavily by Americans, who were known in the parlance of the Chinook Jargon as "Boston men" or simply "Bostons". A settlement developed on the east bank of the river to the north of the confluence with Anderson River. This was later moved to the present site with the construction of Canadian Northern Pacific Railway.