What physical features have acted as barriers to settlement in the United States and Canada?

Answer:- The natural features include Appalachian Mountain, Rocky Mountains, Great Plains, Interior Plains, Canadian Shield. Physical feature mentions to geological element formed by nature such as soil, slopes, lakes, flood plains, oceans, rocks, sands, mountains, valley etc. The physical features producing barrier to settlement refers that they acted as interference to existence of human settlement in the region of United states and Canada. The United States and Canada share the North American continent.