c) Colorado

Colorado is home to the largest sand dunes in North America, located in Great Sand Dunes National Park and Preserve. These dunes, some of which rise over 700 feet, were formed from sand deposits of the ancient Rio Grande and its tributaries. The park’s unique landscape of towering dunes set against the backdrop of the Sangre de Cristo Mountains offers a striking and unusual natural spectacle. Great Sand Dunes National Park and Preserve provides opportunities for a variety of recreational activities, including sand sledding and boarding, hiking, and wildlife viewing.