Sketches adapted from Schmidt (1979).
A Vivo and Jorge (1964) based on Köppen classification.
B Mexican portion by Leopold (1950); U.S. by Russell (1931) based on a modified Köppen classification.
C Contrarias Arias (1955) using the Thornthwaite classification.
D Hunziker et al. in Mabry et al. (1977). Basis is the distribution of creosotebush.
Last Update: 21 December 1999.