Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Pale green represents arid areas that receive an annual precipitation of less than 200 mm; medium green indicates semiarid regions, where the annual precipitation is between 200 and 500 mm; and dark green indicates humid areas, where the annual precipitation is greater than 500 mm.
