Is America a Terminal Environment?

When we think of the classic Western, it's usually set sometime between the end of the Civil War and the beginning of the 20th century or to push it a little bit, maybe World War one. Within those 50 years you see almost every Western scenario ever written. And it's a terminal environment because when the Civil War ended, that was the time when America as a nation decided. Okay, the West is now open. There's no more internal conflict about who owns the West. The only thing that might be a little bit controversial is how we're going to conquer the Western lands away from the indigenous people and make it European. So everyone on that in that environment is going to die