THE AMERICAN SOUTHWEST DEFINED

As most of the material contained in this web site deals with the various species of reptiles, turtles, crocodilians, and amphibians native to the Southwestern United States or as it is frequently called the American Southwest, we should define what constitutes the American Southwest.

Definations of this region of the United States vary greatly from source to source depending on whom you are talking to. About the only thing that that you can expect to get an unamious agreement on is that the states of Arizona and New Mexico make up at least part of this region. Beyond those two states, the boundaries of the American Southwest become somewhat hazy. Most people from the Eastern United States consider Texas and Oklahoma to be a part of the American Southwest, while many of those living in California and Arizona consider Texas to be part of the Deep South. Some scholars consider California, Nevada, Utah, Arizona, New Mexico, Colorado, Texas and Oklahoma to all be Southwestern states.

For our purposes here at the Southwestern Center for Herpetological Research (SWCHR), we define the American Southwest as being only the states of Arizona, California, New Mexico, Nevada, Texas and Utah. While we do recognize that certain parts of California, Nevada, Texas, and Utah do not contain the geologic and other natural features that are generally associated with the American Southwest, we have opted to include those states in their entirety for the sake of having a more easily defined border for the region.

Nine different geomorphic or physiographic provinces exist within the six states that have designated as being part of the American Southwest. Those nine physiographic provinces are the Great Plains province, Atlantic Coastal Plain, Central Lowland, Southern Rocky Mountains, Colorado Plateaus, Basin and Range province, Cascade Sierra Mountains, Pacific Border province, and Lower California province (U. S Dept. of the Interior, U.S. Geological Survey). It is also worth noting that four deserts (Mohave, Sonoran, Great Basin, and Chihuahuan) are found within the boundaries of these six states and that four of the states border Mexico to the south.

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