Everyone knows the expression “stubborn as a mule.” More than a tired cliché, however, that is a doltish misperception, foisted upon us by the least adept of mule-handlers. In the words of a real expert, it is “a classic example of man ascribing stupidity to the beast instead of to himself.”

On this Labor Day weekend, think of the great labor that Missouri’s official state animal—the plucky, hard-working mule (not to be confused with the donkey, the symbol of the Democratic Party)—performed for our nation in the opening of the west.

Setting out in covered wagons from Saint Joseph, Independence, and other Missouri cities, more than 400,000 pioneers made their way to the Pacific during the 1840s and 50s. Most people have a mental picture of horses pulling the load. But mules did most of the work, even if horses got most of the credit, thanks to later Hollywood westerns. Movie-makers repeated the mistake in their depiction of stagecoach travel in the 1860s and 70s. In reality, once again, the indefatigable mule, not the more fragile and easily tired horse, was the draft animal of choice.

The above-quoted Rinker Buck tells these stories (and many more) in his book The Oregon Trail: A New American Journey. In 2011, Rinker and his brother Nick stopped in Jamesport, Missouri, to purchase three Missouri mules. Having also acquired a rig (a genuine prairie schooner), they then hit the trail—travelling the whole 2,100-mile length of the Oregon Trail from St. Joe to the Willamette Valley. The two brothers were the first in more than a century to complete the journey.

Just over the Kansas border into Nebraska, a fierce storm forced the brothers to camp in the equipment shed of an abandoned farm. In a book filled with hair-raising (and often hilarious) adventures, this was a fairly commonplace occurrence. It might have gone unremarked except that the same storm system that passed over their heads levelled Joplin, Missouri, a few hours later.

I have my own tenuous connection with mules. In his 16th summer, my brother Harry worked in the Bootheel—driving a team of mules in clearing tree stumps from a field. He was mule-struck upon returning home . . . telling stories that filled me, the younger brother, with a mixture of envy and awe. For his 71st birthday this June, I gave Harry the Oregon trail book. He returned it to me no more than a week later—saying it was wonderful. He wanted to be sure that I read it as well.

A cross between a female horse (mare) and a donkey (jack), mules combine the greater size and strength of the mother with the lighter weight, agility, and more feral instincts of the father. Mules require only half the feed of horses. They can travel long distances without water. Most of all, as Rinker Buck writes, “They love to work.”

With a keen sense of smell, they are uncommonly alert to danger. On the trail they saved countless lives in picking up the scent of buffalo herds and packs of coyotes long before they became visible to people. At the approach of predators, mules sounded the alarm, perking their long ears forward, staring in the direction of the threat.

As for their supposedly difficult behavior, or “mulishness,” that too, is a product of superior instincts. Unlike the happy dog or the pliant horse, the clever and independent-minded mule will not plunge willy-nilly into a rushing stream. It prompts the muleteer to show that the next step is safe by riding a horse across or wading in himself. “Mules ponder matters a lot,” Buck writes.

This Labor Day, let’s thank the mule for its super-human (and super-smart) efforts on our behalf. It played a critical role in uniting our country from sea to shining sea.