R.C. Cooper had used mules in freighting from Missouri to Colorado, and later, did freighting in Colorado when he lived there. He considered them to be "tougher" than horses under unusual conditions and in new or strange places. He knew that they would not overeat or drink when they were too warm and get "foundered" as horses often do. And they would have to be driven by different men.
Tales of the numbers of mules and horses that Cooper owned were sure to grow with repetition. But the number listed with the assessor, or given in security for a mortgage would seem to assure that he had at least the number listed for these purposes. Just how many he bought when he "outfitted" in Fargo in 1880 is not known. No doubt it was the smallest number he could get along with and provide tent shelter for, until his first barn was built. But about five months later, in the spring of 1881, five cars of "about eighty mules from Missouri" came to Sanborn. "Cooper had more than one hundred horses and mules to begin with." (William Glass, who came in spring of 1881).
In the late winter or early spring (of 1881) T.J., Rollin, and Charles Cooper went to St. Louis for the five carloads of mules. Charles and some other men had charge of these mules, and when they reached Tower City they were delayed for two days by a severe blizzard. They had to board up the boxcars with canvas and boards to keep the cold and wind off the mules, unaccustomed to the severe cold. T.J. Cooper and his brother, Rollin, had gone ahead of the freight, on to Sanborn where they waited for Charles. Everything had to be hauled from Sanborn to the farm in 1880-81.
In 1884 horses and mules were assessed at an average of $60 each. Cooper Brothers were assessed $980 on their horses, or about 20, and $4020 on their mules, or about 80 head. (All assessor's and mortgage data are from courthouse records). In 1896 Mr. Cooper bought twenty-five mules shipped in from Montana. (Courier, July 31, 1896).
While his harvest crew were cutting around a Section of Cooper's wheat near the railroad south of Cooperstown with about 30 binders, a hand car of railroad workers went by and stampeded the mules on the binders into a run-away of the whole outfit. The mules ran forward and jumped into the canvas and wooden platform of the binder ahead. It took two or more days to make the necessary repairs of broken and metal parts.
Source: Cooperstown, North Dakota 1882-1982 Centennial page 39