North America's fastest mammal, the pronghorn can accelerate explosively from a standing start to a top speed of 60 miles per hour--but it can also cruise at 45 miles per hour for many miles. What accounts for the speed of this extraordinary animal, a denizen of the American outback, and what can be observed of this creature's way of life? And what is it like to be a field biologist dedicating twenty years to studying this species? In Built...