Here's why:

* Cascade Range: This mountain range in the Pacific Northwest is known for its volcanic peaks, including Mount Rainier and Mount Hood, which reach elevations over 14,000 feet.

* Mojave Desert: This desert in Southern California is known for its low elevation and arid climate. The highest point in the Mojave Desert is Telescope Peak at around 11,049 feet.

* Ozark Plateau: This plateau in the central United States has a relatively low elevation compared to the Cascade Range. The highest point is Buffalo Mountain at around 2,600 feet.

Therefore, the Cascade Range has the highest overall elevation, followed by the Mojave Desert, and then the Ozark Plateau.