A series of droughts known as the Dust Bowl occurred in 1930-1931, 1934, 1936, and 1939-1940, leaving no recovery time in between them. The 1934 North American drought was the widest spread and driest in 1,000 years according to a study published in the Oct. 17 edition of Geophysical Research Letters. Researchers from NASA and the Lamont-Doherty Earth Observatory in Palisades, New York, used a tree-ring based drought record between the year 1000 and 2005. They also used records that had been kept whenever available. They determined the 1934 drought was 30 percent more severe than the drought named the second worst (in 1580). The 1934 drought had a much wider reach than the recent 2012 drought. The 1934 drought extended across 71.6 percent of western North America while the lesser 2012 drought extended across 59.7 percent.
Normally droughts in the west tend to be very regional, which is what makes the 1934 drought particularly exceptional.