The greatest environmental disaster in American history lasted for eight years and displaced more than 3 million people. What was it?

The Dust Bowl—which refers both to this event and the place where it happened: some 100 million acres in Kansas, Colorado, Oklahoma, New Mexico, and Texas.

This area normally sees just 20 inches of rain a year. High winds from the Rocky Mountains roll across it. Summers bring scorching heat; winters bring Arctic blasts from Canada.

Explorers called it the Great American Desert and avoided it.

But in the late 1800s, agents from the government, eager to push development westward, rebranded it “the Great Plains.”

Anyone with an $18 filing fee could stake a homestead. People came in droves and found an ocean of native grasses.

These grasses had developed to withstand the prairie’s harsh conditions. Over thousands of years, they created the topsoil, held it in place against the wind, and trapped moisture to withstand periodic droughts.

But to the inexperienced farmers, it just looked like grass. They burned it or plowed it under, and planted wheat and other crops.

Grain production soared and the expansion seemed a success. Over the next 50 years, millions more settlers arrived.

Then, in 1929, the Great Depression hit. Grain prices collapsed. Worse, in 1931, the rains stopped.

What followed was a disaster of epic proportions, which we’ll cover in our next installment on the Dust Bowl.