See quotations.
1878. The mountain bronchos [are] selected for their skill in going up high and narrow ways…. Our bronchos carried us with ease and safety; for one of these native horses could easily go up and down any stairs in Cincinnati.—J. H. Beadle, ‘Western Wilds,’ pp. 453–4.
1883. A ragged, tough broncho horse.—E. Ingersoll, ‘The Sequel to an Old Romance,’ Harper’s Mag., lxvi. p. 428/1 (Feb.) (N.E.D.)
