The Western United States usually refers to the following States: Idaho, Montana, Nevada, Utah, Wyoming, Arizona, New Mexico, Oregon, Washington State and California. The West is the largest region of the country and therefore there are large geographical differences. There are rain forests in the Northwest, the highest peaks (such as the Rocky Mountains and the Sierra Nevada), the western part of The Great Plains ' and all the deserts in the United States. The landscape is also characterized by wide highways and open space. The region is home to most of the Native American population in the U.S. in large reserves. The largest cities in the region are: Los Angeles, San Diego, San Francisco, Seattle, Denver, Phoenix, Tucson, Albuquerque, Las Vegas and Salt Lake City. Also many rivers such as the Mississippi, the Missouri river and the Colorado river, flows through this area. Usually the weather is warm and quite dry, but in some parts there can also be a lot of snow and rain fall. It is an unstable climate. Also the temperatures differ very much. On the west coast they have warm summers and mild winter with no to little snow. In the desert area in the Southwest the summers are very hot and the winters are mild, but in the mountains there can be quite a lot of snow falling. More in the Interior, in the North, the summers are warm to hot and the winters can be freezing cold.