The valley once contained what is known as the Okanogan Lobe of the Cordilleran Ice Sheet. Rocks, sandy patches, and gravelly areas indicate thousands of years of glacial action.

Broad-leafed cottonwood, thicketed birches, willows, alders, and aspen (quaking asp), with their smooth, greenish-white bark and easily agitated leaves, line the banks of the Okanogan River. Many of these are of commercial value. The willow, flexible and easily cut, is used by Native Americans in weaving baskets; cottonwood, a soft wood, is especially suitable for paper pulp; aspen wood, because it is odorless, is much used for cheese boxes and butter boxes.

One of Frederic Remington’s paintings of a generation ago pictured a group of Native Americans, sitting languidly astride “cayuses” that were drinking at the willowed riverside of the Okanogan. Other natives appear in the background on the bench above the river, stolidly facing the noonday sun and gazing at the fences of the white settlers, the desolate range, the silent mountains and desert. Owen Wister immortalized these men of the Okanogan in a description beneath Remington’s picture.

Of old, when Okanogan ran
Good medicine for horse and man,
The winged shaft was wont to fly
In peace or war, beneath the sky.
Gone is the arrow, and instead
The message of the white man’s lead,
The poison of the white man’s drink—
These lessons by the river-brink
Are learned, where Okanogan ran
Good medicine for horse and man.