Answer: overused water resources.
Explanation:
Sun Belt basically includes the states of the South and the Southwest. Sunbelt describe both the warm climate of these regions and the rapid economic and population growth .
The migration explotion did not come with constant and balanced development throughout the Sun Belt and some states and subregions have lagged behind, in part, because of the resources that are being used by the increasing population, including the water resources. This has also led to some of these subregions to be taken as some of the most poor, and are lagging behind other northern and western states as sources of opportunity for migrants.