For 20 years during the pioneering age of Canadian aviation, an aluminum-bodied bush plane soared over northern forests and remote lakes as part of a government mission to map and monitor the country's uncharted backwoods.

Now, 80 years after Canadian forestry officials purchased the U.S.-made Hamilton Metalplane from a Boeing plant in Wisconsin, the meticulously refurbished and flyable aircraft -- the only one of its kind in the world -- is expected to sell for at least $1-million later this month at a major Arizona auction of vintage cars and planes.

Described by the Barrett-Jackson auction house as "one of the rarest and most beautifully restored classic aircraft in the world," the award-winning antique is the lone intact survivor from an original production run of just 29 planes.