Which South American desert is often called the driest non-polar desert?

The Atacama Desert is often called the driest non-polar desert on Earth.

It occupies a long strip along the Pacific coast of northern Chile, between the coastal mountains and the Andes. Its extreme dryness comes from several influences working together: the cold north-flowing Humboldt Current, persistent high atmospheric pressure and a double rain-shadow effect that blocks moist air from both the Pacific and the Amazon Basin.

The desert stretches for roughly 1,600 kilometers, although estimates vary depending on where its boundaries are drawn. Some locations receive only a few millimeters of rain annually, and certain weather stations have recorded extraordinarily long rainless intervals. The Atacama is so Mars-like that scientists have used its terrain for planetary-environment research and rover testing.

“Driest non-polar desert” is more precise than simply “driest place on Earth.” Parts of Antarctica's McMurdo Dry Valleys are drier overall because they are polar. The Atacama also is not lifeless: fog, underground water and occasional rainfall support specialized plants, lichens and dramatic “flowering desert” events.