Final answer:
The most widespread environmental issues in the Southwestern United States are water scarcity and pollution, compounded by population growth and urbanization.
Step-by-step explanation:
Within the Southwestern United States, the most widespread environmental issues are related to water scarcity and pollution. The Southwest, including parts of Texas, New Mexico, and Arizona, is characterized by an arid climate with limited rainfall. Growing urban areas, agriculture, and industrial activities are putting a significant strain on already scarce water resources. In addition, water quality is threatened by chemical pollution from various sources such as agriculture, industry, and mining.
Over the past few decades, the region has witnessed a population surge due to Sun Belt migrations, exacerbating the demand for water and waste management. Water management has become a hot-button political issue, particularly in arid states like Nevada and in cities such as Las Vegas that get most of their water from Lake Mead. The high urban population concentrations accentuate the need for sustainable access to clean water and clean air, highlighting the importance of effectively addressing these environmental challenges.