The book details the multifaceted harm caused by roads, extending far beyond the estimated one million animals killed by vehicles daily in the U.S. alone. Roads fragment habitats, preventing creatures from migrating for food and mates; they serve as conduits for invasive species; and their associated salt runoff and traffic noise pollute ecosystems. Goldfarb showcases projects like wildlife bridges in California and tunnels for toads in England, demonstrating how thoughtful design can mitigate destructive effects. Grizzly bears tend to use large, open overpasses, while black bears and cougars often favor the cover provided by smaller underpasses.