Given that our forebears slaughtered buffalo during the 19th century in a kind of wildlife holocaust, this all-American iconography is perverse and somewhat depressing. Perhaps it's an expression of a deep national guilt, an attempt to expiate an original sin. There were once so many buffalo in this country—they numbered, by some estimates, as many as 60 million—that a single herd on the High Plains could be seen for a hundred miles. "Of all the quadrupeds that have lived upon the earth, probably no other species has ever marshaled such innumerable hosts," conservationist William T. Hornaday wrote in his classic 1889 monograph The Extermination of the American Bison. "It would have been as easy to count [the] number of leaves in a forest as to calculate the number of buffaloes." Bison were happiest on the grasses of the prairies and the plains, though they lived in almost every state in the lower 48, from Maine to Florida, from the eastern tidewater to the Rocky Mountains, from Texas to Montana. As measured by biomass, they may have comprised the largest-ever concentration of an animal species on the planet.