The Chinchaga fire, also known as the Wisp fire or the Chinchaga River fire, was a forest fire that burned in northern British Columbia and Alberta in the summer and early fall of 1950. With a final size of between 1,400,000 hectares (3,500,000 acres) and 1,700,000 hectares (4,200,000 acres), it is the single largest recorded fire in North American history. The fire was allowed to burn freely, a result of local forest management policy and the lack of settlements in the region. The Chinchaga fire produced large amounts of smoke, creating the "1950 Great Smoke Pall", observed across eastern North America and Europe. As the existence of the massive fire was not well-publicized, and the smoke was mostly in the upper atmosphere and could not be smelled, there was much speculation about the atm