d

Climate:
mostly temperate, but tropical in Hawaii and Florida, arctic in
Alaska, semiarid in the great plains west of the Mississippi River,
and arid in the Great Basin of the southwest; low winter
temperatures in the northwest are ameliorated occasionally in
January and February by warm chinook winds from the eastern slopes
of the Rocky Mountains

Terrain:
vast central plain, mountains in west, hills and low mountains in
east; rugged mountains and broad river valleys in Alaska; rugged,
volcanic topography in Hawaii

Elevation extremes:
lowest point: Death Valley -86 m
highest point: Mount McKinley 6,194 m

Natural resources:
coal, copper, lead, molybdenum, phosphates, uranium, bauxite, gold,
iron, mercury, nickel, potash, silver, tungsten, zinc, petroleum,
natural gas, timber

Land use:
arable land: 19.13%
permanent crops: 0.22%
other: 80.65% (2001)

Irrigated land:
214,000 sq km (1998 est.)

Natural hazards:
tsunamis, volcanoes, and earthquake activity around Pacific Basin;
hurricanes along the Atlantic and Gulf of Mexico coasts; tornadoes
in the midwest and southeast; mud slides in California; forest fires
in the west; flooding; permafrost in northern Alaska, a major
impediment to development

Environment - current issues:
air pollution resulting in acid rain in both the US and Canada; the
US is the largest single emitter of carbon dioxide from the burning
of fossil fuels; water pollution from runoff of pesticides and
fertilizers; limited natural fresh water resources in much of the
western part of the country require careful management;
desertification

Environment - international agreements:
party to: Air Pollution, Air Pollution-Nitrogen Oxides,
Antarctic-Environmental Protocol, Antarctic-Marine Living Resources,
Antarctic Seals, Antarctic Treaty, Climate Change, Desertification,
Endangered Species, Environmental Modification, Marine Dumping,
Marine Life Conservation, Ozone Layer Protection, Ship Pollution,
Tropical Timber 83, Tropical Timber 94, Wetlands, Whaling
signed, but not ratified: Air Pollution-Persistent Organic
Pollutants, Air Pollution-Volatile Organic Compounds, Biodiversity,
Climate Change-Kyoto Protocol, Hazardous Wastes

Geography - note:
world's third-largest country by size (after Russia and Canada) and
by population (after China and India); Mt. McKinley is highest point
in North America a