Death Valley National Monument was declared a U.S. National Monument in 1933, placing the area under federal protection. In 1994, the monument was redesignated a national park, as well as being substantially expanded to include Saline and Eureka valleys.
It is the hottest and driest place as well as the lowest point in North America. Daily summer temperatures of 120 °F (49 °C) or greater are common, as well as below freezing nightly temperatures in the winter. The hottest air temperature ever recorded in Death Valley was 134°F (57.1°C) on July 10, 1913, at Furnace Creek. It is also the official highest temperature in the Western Hemisphere.
It is Death Valley's unique geography that creates extreme heat. Winds off the higher surrounding land, known as the Great Basin, often blow hot, dry air thousands of feet down into the long, narrow valley, which is 282 feet below sea level. As the air moves downhill it encounters increasing atmospheric pressure, which squeezes the air, warming it at a rate of 5.5° for every 1,000-foot drop in elevation. Some of the mountain ranges around Death Valley are 7,000 - 9,000 feet high, and the surrounding land between the ranges is 4,000 - 5,000 feet above sea level, which means the air can warm at least 20-25° by the time it reaches the bottom of the valley.