What mountain range is the oldest in the U.S?

The oldest mountain range in the U.S. is the Appalachian Mountains. Formed over 480 million years ago during the Ordovician period, the Appalachians were shaped by tectonic activity and erosion over millions of years. Stretching from Canada down to Alabama, they are characterized by their rolling hills and diverse ecosystems, making them a significant geological and ecological feature of the eastern United States.