The big burn of 1910---
Coeur d’Alene National Forest in Idaho near the Little North Fork of the St. Regis River. While the 1910 fire was devastating to parts of Idaho, it also burned large sections of forest land in Western Montana, including the Flathead Valley.
Sorry, just noticed that this answer was given already
There ya go, Derek. Props to Mike France and David Lord for zeroing in on this maelstrom, as well.
A century ago this week, 3 million acres of North Idaho, Montana and Washington forest were turned to charcoal in two wind-whipped days.
The summer of 1910 was hot and dry like no other. The resultant drought left plenty of dry vegetation in the forests of northeast Washington, northern Idaho, and western Montana. By mid-August there were 1,000 to 3,000 fires already burning due to hot cinders flung from locomotives, sparks, lightning, and backfiring crews.
Then came the wind.
On August 20, a cold front swept through the area bring hurricane-force winds which blew all the smaller fires into one or two gargantuan blazes- far too huge for the U.S. Forest Service- then only 7 years old- to handle with little manpower, and even less resources.
Some firsthand accounts from rangers who lived through the horror:
"They told of trees swelling, sweating hot sap, and then exploding; of horses dying in seconds; of small creeks boiling, full of dead trout, their white bellies up; of bear cubs clinging to flaming trees, wailing like children."
For two days, the conflagration consumed nearly three million acres of forest (roughly the size of Connecticut), killing 87 people, 78 of them firefighters.
The scale was immense. Telegraph operators sent out desperate messages describing the approach of a solid line of flame 30 miles wide, and that was no exaggeration. Today, you can drive Interstate 90 east from Wallace, Idaho to just short of St. Regis, Idaho — about 45 miles — and be within the old burn zone every mile of the way. And this was by no means the only burn zone in the Northern Rockies – just the biggest.Smoke from the fire was said to have been seen as far east as Watertown, New York and as far south as Denver, Colorado. Ships 500 miles out into the Pacific Ocean, could not navigate by the stars because the sky was cloudy with smoke.
The fire had no end in sight and would have burned on had Mother Nature not returned to the scene with another cold front containing dousing rains. By the time it was over,
The legacy of The Big Burn was the re-shaping of the U.S. Forest Service.
Prior to the fire, debates like those that remain today were taking place: let the fires burn as nature intended, or fight them in order to protect the forests. However, after the devastation of this fire it was decided that the U.S. Forest Service was to prevent and battle against every wildfire.
Firefighters across the nation are gathering to mark the centennial of the event this weekend. Numerous events are planned around the region to commemorate lost lives, reflect on a century's worth of changes in wildland fire management philosophy, and celebrate how far we've come.
The 1910 Fires
One of the largest forest fires in the history of the United States swept over Idaho and Montana on August 20 and 21, 1910 including the area where you now stand. The fire burned three million acres, destroyed eight billion board feet of timber and killed 86 people. Hurricane-force winds shot fireballs for miles across the mountains. The sky turned dark as far east as Colorado
I'm with Derek here.
Although I agree that "largest" doesn't necessarily mean square area. "Largest" loss of life Peshtigo. Largest dollar loss, Largest FF loss, and so forth. Next time, please specify.