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: 18.01%
permanent crops: 0.21%
other: 81.78% (2005)

Irrigated land:
223,850 sq km (2003)

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 and Death Valley the lowest point on the continent

People United States

Population:
298,444,215 (July 2006 est.)

Age structure:
0-14 years: 20.4% (male 31,095,847/female 29,715,872)
15-64 years: 67.2% (male 100,022,845/female 100,413,484)
65 years and over: 12.5% (male 15,542,288/female 21,653,879) (2006
est.)

Median age:
total: 36.5 years
male: 35.1 years
female: 37.8 years (2006 est.)

Population growth rate:
0.91% (2006 est.)

Birth rate:
14.14 births/1,000 population (2006 est.)

Death rate:
8.26 deaths/1,000 population (2006 est.)

Net migration rate:
3.18 migrant(s)/1,000 population (2006 est.