Drought in the United States: Causes and Current Understanding

Summary

This report discusses how drought is defined (e.g., why drought in one region of the country is different from drought in another region) and why drought occurs in the United States. It briefly describes periods of drought in the country's past that equaled or exceeded drought conditions experienced during the 20th century. This is followed by a discussion of the nature and extent of recent droughts that affected Texas and the U.S. midcontinent, and the current drought in California. Lastly, the report discusses future prospects for a climate in the western United States that might be drier than the average 20th-century climate and the possible influence of human-induced climate change.