Natural environment

The North American Southwest lies mostly in the tropical and subtropical continental or extremely dry climate zones along with varieties of climates or microclimates typical of upland and mountain areas. The climate of this region is generally very dry, although there is much more rain and humidity in the higher mountain ranges. Precipitation is not evenly distributed throughout the entire territory of the Southwest, with areas close to the steppes and mountains receiving more—i.e. in the middle and east of the region (with an average rainfall of even 500 mm per year)—than in the desert areas located in the western and southern area of the Southwest (rainfall does not exceed 150–200 mm, and can be much less).

Two types of rainfall concentration, or “rainy seasons”, can be distinguished in the Southwest (Cordell 1997). The first is characterized by the presence of two such rainy seasons: summer (July-August) and winter (December-March, reaching its peak in February) in the western part of the region, i.e. in Arizona, southern Utah and Nevada, southwestern Colorado, eastern California and Mexican Sonora.

Although the Southwest, in popular imagination, is mainly associated with desert landscapes crisscrossed by canyons, in reality it is not so homogeneous and includes at least four different physical and geographical provinces: 1) the central and north-central part of the Southwest (including the Four Corners region) is located in the Colorado Plateau; 2) to the north and east, the Colorado Plateau is bordered by southern province of the Rocky Mountains encompassing, among others, the ranges of the San Juan Mountains and the Sangre de Cristo Mountains (southern Colorado and northern New Mexico); 3) the western and southern Southwest, from the central and western parts of Arizona and New Mexico is the Basin and Range Province; the two largest deserts in this region are the Mojave and Sonora; 4) The fourth physical and geographical sub-region in the eastern part Southwest is the western area of the Great Plains.

The vegetation of the Southwest varies by sub-region. The wood of many species was used to construct houses; the seeds and nuts of plants, e.g. juniper and pinion pine, were harvested and eaten; food and drink (including alcoholic beverages) were prepared from cactus flowers, leaves and fruit, while many plants were also used in herbal medicine and medicine. Knowledge of herbs and plants is one of the elements involved in cultivating ancient traditions, for the Pueblo, Apache, Navajo and Ute Indians, amongst others. Yucca was used to make many everyday objects, such as baskets, containers, items of clothing, sandals, ropes and other items. Wood was also harvested for fuel and for making various types of equipment and utility items.