Wildfires across the western United States have been getting bigger and more frequent over the last 30 years. The total area these fires burned increased at a rate of nearly 90,000 acres a year -- an area the size of Las Vegas, according to the study. Individually, the largest wildfires grew at a rate of 350 acres a year.
http://www.sciencedaily.com/releases/2014/04/140417151229.htm