GENERAL KNOWLEDGE

Detailed explanation-1: -The Great Plains of North America are a large, flat area of the United States and Canada that extends from the Rocky Mountains to the Appalachian Mountains.

Detailed explanation-2: -Lesson Summary. The United States is home to a large variety of landforms including mountains, hills, plateaus, plains, rivers, lakes, valleys, and canyons.

Detailed explanation-3: -These include the Great Lakes Water Quality Agreement to protect water quality and ecosystem health and the Columbia River Treaty regime. The United States and Canada developed the Columbia River Treaty regime to regulate the flow of the Columbia River to benefit both countries.