The great plains were overrun with millions of bison (the American buffalo) in 1491. They were a way of life for Native Americans in the region. By the mid-nineteenth century, with the railroad boom, both the the railroad's biggest threats were Native Americans and bison, and vice versa. Something had to give. The railroads won out at the expense of the Plains Indians' ways of life, and especially the bison.
Please review the "How Stuff Works" podcast, What Saved the American Bison?
Once you're done, complete the reflection and response. Students can earn extra credit by by demonstrating their learning from the podcast beyond the in-class discussion.