Answer:
The dry climate of the region.
Explanation:
Southwestern United States is a region of the United States. Culturally, the states clearly influenced by Mexico, such as Texas, New Mexico and Arizona, are considered to be part of this region. Southern Nevada and parts of Colorado and California are often included in it.
This region is an arid and hot zone, in which several deserts coexist, such as the Mojave Desert and the Sonoran Desert. It is the driest area in the nation, which historically limited the demographic development of the region, with which today, as a consequence, the states of the Southwest have a low population density, concentrated mainly in large cities such as Phoenix, Houston, El Paso or Albuquerque.