Entomology definition of Upper Sonoran faunal area: that arid part of upper
austral west of 100th meridian; covers most of plains in eastern
Montana and Wyoming, s. w. South Dakota, west. Nebraska, Kansas,
Oklahoma and Texas, and east. Colorado and New Mexico; covers
plains of Columbia, Malheur and Harney in Oregon and Washington.
In California encircles Sacramento and San Joaquin Valleys and
forms a narrow belt around Colorado and Mohave deserts. In Utah
covers Salt Lake and Sevier deserts. In Idaho the Snake plains.
In Nevada and Arizona irregular areas of suitable elevation.