The Big Burn, 1910
What's believed to be the largest wildfire in U.S. history swallowed up 3 million acres of woodlands in Washington, Idaho and Montana. Small fires were no surprise in the early 20th century, with lightning strikes and railroad sparks constantly igniting tinder in the forests. But in mid-August, after an overly dry summer that saw just one inch of rain, an unexpected cold front from the north whipped through the northern Rocky Mountains, with 75-mile winds merging already-burning small fires into one giant inferno. Scorching an area the size of Connecticut, the fast-moving fire raged for two days, on August 20 and 21, 1910. Seventy-eight firefighters and at least seven residents died as a result of the ravaging flames, and thousands more were impacted by the fire's fallout. Smoke from the blaze traveled for hundreds of miles in all directions, clouding the air in western New York and blinding ships in the Pacific Ocean.