The 1950s Drought in the Southwest. In the Southwest, the period 1951-1956 was the worst drought of the 20th century. The 1950s drought was characterized by hot, dry summers followed by dry winters in 1951, 1953, 1954, and 1956; moreover, during the 1950s there was a lull in the frequency of El Niño events. In the Southwest and northern Mexico, massive vegetation dieoffs occurred from the lowland deserts well into the conifer woodlands of the uplands, testimony that even drought-adapted species were overwhelmed by the drought. The drought altered the composition age structure of pinyon-juniper woodlands in central and southern New Mexico. In addition, the 1950s drought may have played a major role in accelerating shrub invasion of grasslands. The map shows areas in the Southwest where precipitation was less than 85% of the record mean as of 1941 for 8 or more years (hatched areas) and for 10 or more years (black areas) during the period 1942-1956. The time series is the areally weighted annual average precipitation over the Southwest, 1895-1988. Note the depth and duration of the 1950s drought.

Credit: Tom Swetnam and Julio Betancourt, from their 1998 paper, "Mesoscale disturbance and ecological response to decadal climatic variability in the American Southwest," Journal of Climate 11:3128-3147; after H.E. Thomas, 1962, "The meteorological phenomenon of drought in the Southwest: Drought in the Southwest, 1942-1956." U.S. Geological Survey Prof. Paper 342A, 43 pp.