I have used Flores, "Bison Ecology," 47, 481, of six million out of an earlier eight million rather than Isenberg, Destruction of the Bison, 138, which has the higher number of 15 million following the Civil War.

Hornaday provides the four million figure. The northern herd was considerably smaller.

William Temple Hornaday, The Extermination of the American Bison (Washington, [D.C.]: Smithsonian Institution Press, 2002, orig. ed. 1889), 504.