Explainer: How this year's destructive U.S. West wildfire season came to be

FILE PHOTO: A U.S. flag is taped to the pole at the entrance of a house destroyed by fire in the aftermath of the Beachie Creek fire near Gates, Oregon, U.S., September 14, 2020. REUTERS/Shannon Stapleton

(Reuters) - Dozens of conflagrations have raged across more than 5 million acres (1.6 million hectares) in Oregon, California and Washington state since August, laying waste to several small towns, destroying thousands of homes and killing at least 35 people.[nL1N2GB0ZI]

The region's increasingly dry and overgrown forests have become large-scale tinderboxes over decades while wildfires have become more frequent, more intense and more deadly. Here's why.