Mustang
2 of the 6 encyclopedias on this shelf carry an entry for Mustang. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
a general name for the wild horses of the pampas and prairies. They are descended from horses brought to the New World by the Spaniards. The term mustang is used chiefly from Mexico southward among Spanish-speaking people. In the Northwest mustangs are known as Indian ponies or broncos. The name cayuse (ki-us), also in use, belongs properly to the ponies of the Cayuse Indians of the northern Rocky Mountains . Broncos are tough, wiry horses of small size. Bronco "busting," or breaking to the saddle, is an operation in which the cowboy takes great pride. The animal is caught with a lasso and thrown to the ground, a saddle is strapped on its back, the rider takes his seat, and the wild, thoroughly terrified animal is given its head. It usually springs to its feet and attempts to throw its rider by every possible trick, especially by "bucking" or leaping into the air and coming down on all four legs held stiff. It rears, it plunges, falls down, rolls over, and attempts in every way to dislodge its rider. Once broken in, however, a bronco is a valuable saddle animal, able to subsist on scant forage and to carry its rider with a tireless lope for hours at a time. It was much employed in scouting, and for cavalry mounts, and has long been a favorite herder's horse. Broncos are broken to the harness as well, but seldom become entirely gentle.
Collier's New Encyclopedia (1921)
the small wild horse of southwestern United States and northern Mexico. It is supposed sed that the mustangs are descendants of Spanish horses which escaped from domestication in Mexico, and became the parents of the immense herds which afterward occupied the plain and prairie regions of the N.
What Has Changed in the Last Century
Aiton's in 1910 described mustangs as a general name for the wild horses of the pampas and prairies, still numerous enough to supply cavalry mounts and herders' saddle horses; Collier's in 1921 spoke of the "immense herds" they had founded. Those herds were largely destroyed in the decades that followed, rounded up for hides, chicken and dog food, and by the mid-20th century free-roaming horses in the American West numbered in the low tens of thousands rather than millions. Congress reversed course with the Wild Free-Roaming Horses and Burros Act of 1971, which made them federally protected; the Bureau of Land Management now counts them, gathers surplus animals and keeps tens of thousands more in off-range corrals and pastures, and argues publicly with advocates over how many the range can hold. Genetic work has confirmed the Iberian ancestry both accounts assumed, while showing later infusions of ranch and cavalry stock, and "bronco busting" has moved from a ranch chore the cowboy took pride in to a scored rodeo event.
Written for this edition, 2026.