More digression-
Our mental picture of the cowboy tends to concentrate on the period of the great cattle drives, 1870s, when cattle had to be taken long distances to a railhead, or to the Dakotas to feed corraled Indians after the buffalo essentially were exterminated.
Durham and Jones are correct that the roster on trail drives was small. The trail boss, wrangler, coosie (cocinero), and a few cowboys, some with experience, some not. The crew was white, the cook black, Mexican or white (There were a few exceptions, one is discussed below).
Abilene KS was a loading point; its population was small, serving the yards for the cattle and the crews who brought them to town and the few farmers in the area; reportedly it had a few African-Americans in the holding yards, but I have not been able to verify this.

One of the few Black cowboys on drives to North Dakota and Montana was John Ware, who settled across the border in Alberta. He had worked on ranches, joined trail drives, and eventually settled as a ranchhand on a large holding. Large (6'3"), athletic and self-contained, he came to be accepted by the predominantly Scotch, English and American ranchers who came to this new ranching area which was opening up. He was respected as a hard worker and a good cattleman, and the best broncbuster in the region. Some notes referred to him as Nigger John Ware, but this was typical of the time, when the Encyclopedia Britannica (see 1911 ed.) pointed out physical and mental differences between Negroes and other races, characterizing them as inferior, prone to fights, but with much musical ability.
Ware worked for a spell on two of the large ranches before he was able to buy his own place. His brand, 9999, reportedly stemmed from his age of 9 years when the slaves were emancipated, and he considered it his lucky number. A small bull trout breeder stream which runs through his property, now called Wareabouts by its present owners, bears the name Ware Creek. He is one of the "Fifty Mighty Men" in a book on Albertans by Grant McEwan.
A few other African-Americans were coming to the Canadian prairie; he married the daughter of a carpenter who had settled in Calgary. He later was able to buy a larger spread on the Red Deer River.

On large ranches, conditions were quite different. Texas ranches like the Kennedy have many Mexican-American famillies, some of whom represent the third generation or so living on the ranch. Tex-Mex music is often heard.
I don't have any statistics, but I am sure that some African-American families are equally long-term.

Small ranches are quite different. Typically in Alberta, several will join together at branding times, or on moves from high to lower pastures. Entire families (and sometimes friends and relatives from town) take part in the drives, and in the branding, immunization and castration of calves, and the party that follows. Usually the ranch with good facilities and location is selected, and kitchen duties and liquor costs shared. Two ropers at least are essential to keep the calves coming to where the work is done, and two teams to do the fixin'. Never heard a genyouwine folk song, secular or other, sung at these events, but some country wannabe generally brings a guitar.