Highway 39 is a very minor 29 km (19 mi) long spur from the John Hart Highway northwest to the town of Mackenzie, near the southern arm of Williston Lake. Highway 39 and the town of Mackenzie were both built in the 1960s as a measure of support for workers on the construction project of the W. A. C. Bennett Dam (which actually is not on the same arm of Williston Lake as Mackenzie). The road did not gain its '39' designation, however, until 1975.
