It started when hot autumn winds snapped a power line east of Paradise, California, showering the ground with sparks.
Flames shot up in dry grass near the Feather River, fanned into nearby pine trees and raced 8 miles to town.
Eighty-five people died and nearly 19,000 buildings were destroyed in the Camp Fire, the state's deadliest wildfire.
No one could have anticipated such a catastrophe, people said. The fire's speed was unprecedented, the ferocity unimaginable, the devastation unpredictable.
Those declarations were simply untrue. Though the toll may be impossible to predict, worst-case fires are a historic and inevitable fact.
And the same factors that doomed Paradise also put hundreds of other towns at risk, according to an Arizona Republic and USA TODAY analysis of fire hazards across 760 million acres of the American West.
Of small communities across 11 states, more than 500 have a higher wildfire hazard potential than Paradise, Calif.