William K. Smith Periods of drought in the western United States have become longer over the past 50 years, according to a new study from researchers in the University of Arizona College of Agriculture and Life Sciences in partnership with the USDA Agricultural Research Service. In hopes of understanding how significantly rainfall totals and timing have changed in the past five decades, the researchers analyzed daily meteorological data from over 300 long-term weather stations across the western U.S. "In the West, total annual rainfall has decreased by about 0.4 inches since the 1970s. The average longest dry period has increased by roughly 50% from 20 to 32 days," said co-senior author