Jill Hubley has mapped the causes of wildfires in the United States from 1980 to 2016, based on Federal Wildland Fire Occurrence Data. The map toggles between main causes (human and natural) and specific cause; there’s also a chart ranking the causes.
The highest and lowest ranked causes are highlighted when the chart loads. These represent the cumulative ranking across all years. Lightning, a natural cause, often floats to the top, but that’s only because on the human side, the vote is split between more than twenty options. Lightning doesn’t predominate in all states, though. In Alabama, the number one cause is pyromania. In Indiana, it’s brakeshoes. In Minnesota, it’s field burning. There are a couple of overall trends, too. Smoking is going down as a cause, and powerlines are going up.