Combined wildfire dataset for the United States and certain territories, 1870-2015

The increase in wildfires, particularly in the western U.S., represents one of the greatest threats to multiple native ecosystems. Despite this threat, there is currently no central repository to store both past and current wildfire perimeter data. Currently, wildfire boundaries can only be found in disparate local or national datasets. These datasets are generally restricted to specific locations, fire sizes, or time periods. Our first objective was to create a comprehensive national wildfire perimeter dataset by combining all freely available wildfire datasets that we could download. We combined and dissolved individual wildfire polygons from multiple datasets if they were in the same year and overlapped each other or were within 1km of the fire boundary. This combined dataset includes spatial summary statistics such as number of times burned, earliest fire of record, and most recent fire of record. Our second objective was to create various seasonal weather rasters (for example October-March, April-June, July-September, and October-September precipitation and temperature) using PRISM (http://www.prism.oregonstate.edu/) weather data to identify weather factors from the focal year and 1-3 years previous that may lead to an increase in the number and size of wildfires.