Which North American mountain range is among the oldest on Earth and extends nearly 2,000 miles?

The Appalachian Mountains are among the oldest mountain ranges on Earth, formed over 480 million years ago during the Ordovician Period. They extend nearly 2,000 miles, stretching from Canada down through the eastern United States to Alabama. This ancient range has been shaped by multiple geological events, including tectonic activity, erosion, and glaciation, which contribute to its current landscape.

The Appalachian Mountains feature a wide variety of ecosystems and are known for their biodiversity, which is a direct result of the range's age and geographical variations. Unlike the younger Rocky Mountains, which emerged from tectonic movements much later, the Appalachians are characterized by rolling hills and valleys, having been worn down over millions of years.

The other mountain ranges listed, such as the Rocky Mountains, Sierra Nevada, and Cascade Range, are all much younger in geological terms, formed primarily in the last 60 million years. Each has unique features and histories, but none possess the same foundational age and extent as the Appalachian Mountains.