North America is first featured in Last Killers.
In Last Killers North America is the main location, while Madagascar is the secondary one. Anyhow, it is first seen when a Daspletosaurus stalks a Chasmosaurus. From that point onward, North America is the stage for several dramatic performances, including the dinosaur massacre in the monsoon season. It is never seen again.
1. North America was the home of the most notorious dinosaur ever - Tyrannosaurus Rex. However, Planet Dinosaur decided to cut this infamous killer out of their program, partly because Walking with Dinosaurs had already taken care of that for them, and also because the show was about the more recent dinosaur discoveries.