The American West is burning like never before. In fact, wildland fires have scorched record acreage across the United States. Fighting these wildfires is becoming increasingly expensive, costing upward of $3 billion a year in federal funds. Several factors have contributed to this trend, including nearly a century of aggressive fire suppression has left many western US forests overgrown and extremely vulnerable to wildfire, drought and rising global temperatures, and more people living in areas with a high threat of fire.

In certain cases, fire managers will let fires burn in order to restore some of the natural ecological dynamics. But the priority is to protect human lives and, when possible, to keep neighborhoods from going up in flames. Today there are simply more homes and people than ever before in places likely to burn. Americans are rapidly developing the transition area between the deep woods and existing urban areas—some eight million homes were built in this Wildland Urban Interface, or WUI, between the past two censuses. That's more homes than in all of New York City, and it means a lot more ground for firefighters to protect.