Like the Rockaway, the Bronco is another dance listed under the “Miscellaneous” category in M.B. Gilbert’s Round Dancing (Portland, Maine, 1890) as suitable for either jig time (6/8) or galop time (2/4).
Please see my earlier post on the Rockaway for a discussion of jig and galop rhythms and a sample of jig music.
Original description
Leap backward from the right to left foot, 1; leap backward upon the right foot, 2; leap backward upon the left, 3; pass right to side and immediately draw left to right (à la Newport), & 4; pass right to side and draw left to right, & 5; leap forward upon the right, 6; pass left to side and draw right to left, & 7; pass left to side and draw right to left, & 8; four measures. Repeat, commencing as at first. The second time the right foot may move backward at the sixth count, making the turn to the left. Counterpart for lady.
— Gilbert, Round Dancing, p.165


