Bootleg fire: Dangerous 'fire clouds' form over Oregon By Gillian Flaccus Oregon Bootleg Fire, already largest in US, continues to grow The Bootleg Fire in southern Oregon had grown to over 227,200 acres (about 355 square miles) by July 15, making it the largest in the US, officials reported. (Credit: Ryan Berlin via Storyful) PORTLAND, Ore. (AP) - Smoke and heat from a massive wildfire in southeastern Oregon are creating giant "fire clouds" over the blaze — dangerous columns of smoke and ash that can reach up to 6 miles (10 kilometers) in the sky and are visible from more than 100 miles (160 kilometers) away. Authorities have put these clouds at the top of the list of the extreme fire behavior they are seeing on the Bootleg Fire, the largest wildfire burning in the U.S. The inferno grew Friday to about 75 square miles (194 square kilometers) larger than the size of New York City and was raging through a part of the U.S. West that is enduring a historic drought.