The Great Basin span an area between the Rocky Mountains on the East and the Sierra Nevada and Cascade Mountains on its West and covers most of Nevada and more than half of Utah, as well as parts of California, Idaho, Oregon and Wyoming. North-South mountain ranges are separated by broad basins and valleys. Most of the basin has a semi-arid or arid climate with hot summers and cold winters. The Western areas of the basin tend to be drier than the Eastern areas because of the rain shadow of the Sierra Nevada. Higher elevations tend to be cooler and receive more precipitation. Some dryland and irrigated agriculture occurs in Eastern basins. The two most populous areas are the Salt Lake City area including Provo and Ogden and the Reno area including Sparks and Carson City.