1. The Appalachian Mountains: A range of ancient mountains stretching from Alabama to Maine, known for their forested slopes and rolling foothills.

2. The Great Plains: A vast, flat expanse of grassland that stretches from the Mississippi River to the Rocky Mountains, known for its agricultural importance.

3. The Rocky Mountains: A dramatic range of young, towering mountains extending from Canada to New Mexico, known for their rugged peaks, alpine meadows, and abundant wildlife.