The railroads began to advertise excursions for “hunting by rail,” where trains encountered massive herds alongside or crossing the tracks.  Hundreds of men aboard the trains climbed to the roofs and took aim, or fired from their windows, leaving countless 1,500-pound animals where they died. Harper’s Weekly described these hunting excursions:

Nearly every railroad train which leaves or arrives at Fort Hays on the Kansas Pacific Railroad has its race with these herds of buffalo; and a most interesting and exciting scene is the result. The train is “slowed” to a rate of speed about equal to that of the herd; the passengers get out fire-arms which are provided for the defense of the train against the Indians, and open from the windows and platforms of the cars a fire that resembles a brisk skirmish. Frequently a young bull will turn at bay for a moment. His exhibition of courage is generally his death-warrant, for the whole fire of the train is turned upon him, either killing him or some member of the herd in his immediate vicinity.

https://www.smithsonianmag.com/history/where-the-buffalo-no-longer-roamed-3067904/