Which of the following covers the area of the present day states of Washington, Oregon, Idaho and is between the Cascade Mountains on the Pacific coast and the Rocky Mountains?
This is a plateau lying in the northwestern corner of the United States between the Cascade Range to the west and the Rocky Mountains to the east. It experiences a rain shadow effect due to the presence of the Cascade Range and is much drier than the Pacific coastal regions. Despite the relatively dry climatic conditions, the Columbia River flows through the plateau and empties into the Pacific Ocean.
