The Northern Rocky Mountains have sustained wildfire for centuries. Fires are widespread throughout the region during certain years, most recently in 2000, 2003, 2006, and 2007. However, until very recently there was little understanding of whether such years of widespread fire occurred prior to the 20th century or of the role of climate in the occurrence of such years. Penny Morgan, Emily Heyerdahl, and Carol Miller used fire atlases, fire scars, vegetation, and climate data to address this question. They found that climate is clearly associated with the occurrence of widespread fires in the Northern Rockies throughout the 20th century and in prior centuries. Years of widespread fires had warm springs, followed by warm, dry summers. In addition, during the 20th century, widespread fires occurred during the positive phase of the Pacific Decadal Oscillation (PDO). A gap in years of widespread fire occurred during the mid-20th-century in part because climate conditions were generally not conducive for widespread fire. Given projections of future climate change, years of widespread fire are likely to continue to occur. However, simulation results suggest that land management objectives can be met even with substantial increases in fire activity over 20th-century levels.