Geography of the United States
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{| class="infobox" align="right"
|+'''Geography of the United States'''
|-
|colspan="2" align="center" |[[Image:USA topo en.jpg|250px|Topography of the 48 states of the U.S. mainland]]
|-
|colspan="2" align="center" |<small>'''''Relief map of the 48 states of the U.S. mainland'''''</small>
|-
|colspan="2" align="center" style="border-top:1px solid #000000; border-bottom:1px solid #000000;" |'''Area'''
|-
|'''Total'''
|3,717,813 [[square mile|sq mi]]<br />
9,629,091 [[square kilometer|km²]]
|-
|'''Land'''
|3,536,294 sq mi<br />
9,158,960 km²
|-
|'''Water'''
|181,519 sq mi<br />
470,131 km²
|-
|'''Latitude'''
|38°0' N
|-
|'''Longitude'''
|97°0'W
|-
|colspan="2" align="center" style="border-top:1px solid #000000; border-bottom:1px solid #000000;" |'''Borders'''
|-
|'''Canada'''
|5,526 [[mile]]s
8,893 [[kilometer|km]]
|-
|'''Mexico'''
|2,067 miles
3,326 km
|-
|'''Coastlines'''
|12,380 miles<br />
19,924 km
|-
|colspan="2" align="center" style="border-top:1px solid #000000; border-bottom:1px solid #000000;" |'''Maritime claims'''
|-
|'''Contiguous zone'''
|24 [[nautical miles]] (44 km)
|-
|'''Economic zone'''
|200 nautical miles (370 km)
|-
|'''Territorial sea'''
|12 nautical miles (22 km)
|}
The [[United States]] is a nation in the [[Western Hemisphere]]. It consists of forty-eight contiguous [[U.S. state|states]] on the [[North America|North American continent]]; [[Alaska]], an enormous [[peninsula]] which forms the northwestern most part of North America, and [[Hawaii]], an [[archipelago]] in the [[Pacific Ocean]]. It also holds several [[United States territory|United States territories]] in the Pacific & [[Caribbean]]. The country shares land borders with [[Canada]] and [[Mexico]] and a water border with [[Russia]].
==Area==
<!--When editing this section, please note the distinction drawn between TOTAL AREA (i.e., including water) and TOTAL LAND AREA (excluding water), as the rankings change.-->By [[List of countries and outlying territories by total area|total area]] including water, the United States is either slightly larger or smaller than the [[People's Republic of China]], making it the world's third or fourth largest country. Its rank depends on whether one includes two territories claimed by [[India]] but governed by China when calculating China's size. Both China and the United States follow behind [[Canada]] and [[Russia]] in total area. By land area (exclusive of waters), the United States is the world's third largest country, following Russia and China.<ref>Yahoo's chart of countries by land area based on the CIA World Factbook http://education.yahoo.com/reference/factbook/countrycompare/area/3d.html;_ylt=As1XMsN8kgSx746VWazy_s7PecYF</ref> In total area, the United States is:
*three-tenths the size of [[Africa]] (which is a [[continent]]-- not a nation)
*half the size of [[South America]] (which is also a continent not a nation)
*half the size of [[Russia]]
*roughly the same size as [[China]]
*slightly larger than [[Brazil]]
*slightly more than one and a quarter times the size of [[Australia]]
*two and a half times the size of [[Western Europe]]
*roughly 14 times the size of [[France]]
*roughly 39 times the size of the [[United Kingdom]]
== General characteristics ==
[[Image:USA-satellite.jpg|thumb|275px|right|A satellite composite image of the [[continental United States|contiguous United States]]. [[Deciduous]] vegetation and [[grassland]]s prevail in the east, transitioning to [[prairies]], [[boreal]] forests, and the [[Rocky Mountains|Rockies]] in the west, and [[desert]]s in the southwest. In the northeast, the coasts of the [[Great Lakes]] and [[Atlantic seaboard]] host much of the country's population.]]
The United States shares land borders with [[Canada]] (to the north) and [[Mexico]] (to the south), and a [[Territorial waters|territorial water]] border with [[Russia]] in the northwest. The contiguous forty-eight states are otherwise bounded by the [[Pacific Ocean]] on the west, the [[Atlantic Ocean]] on the east, and the [[Gulf of Mexico]] to the southeast. Alaska borders the [[Pacific Ocean]] to the south, the [[Bering Strait]] to the west, and the [[Arctic Ocean]] to the north, while [[Hawaii]] lies far to the southwest of the mainland in the Pacific Ocean.
Forty-eight of the States are in the single region between Canada and Mexico; this group is referred to, with varying precision and formality, as the ''continental'' or ''contiguous'' ''United States'', and as the ''[[Lower 48]]''. [[Alaska]], which is not included in the term ''contiguous United States'', is at the northwestern end of [[North America]], separated from the Lower 48 by Canada. The State of [[Hawaii]] is an [[archipelago]] in the [[Pacific Ocean]]. The capital city, [[Washington, D.C.|Washington, District of Columbia]], is a federal district located on land donated by the state of [[Maryland]]. ([[Virginia]] had also donated land, but it was returned in 1847.) The United States also have [[Political divisions of the United States#Territories of the United States|overseas territories]] with varying levels of independence and organization.
In total area (including inland water), [[Russia]] and Canada are larger than the United States. Ranking for third-largest status is disputed. Some sources (including ''[[Encyclopædia Britannica]]'' and all publications of the [[People's Republic of China]]), list China as larger than the U.S. Many other sources list the U.S. as larger. The dispute appears to [[political status of Taiwan|hinge]] on Taiwan, without which China takes fourth place. Total U.S. area is 3,718,711 [[square mile]]s (9,631,418 [[square kilometer|km²]]), of which land is 3,537,438 square miles (9,161,923 km²) and water is 181,273 square miles (469,495 km²). Ranked by land area, the top countries in order are Russia, China, the U.S., and Canada.
==Physiographic divisions==
{{Cleanup-section|date=May 2007}}
{{main|United States physiographic region}}
[[Image:MountMcKinley BA.jpg|thumb|right|[[Mount McKinley]], [[Alaska]], the highest point in [[North America]] at 20,320 ft (6,194 m)]]
The eastern United States has a varied topography. A broad, flat coastal plain lines the Atlantic and Gulf shores from the Texas-Mexico border to New York City, and includes the Florida peninsula. Areas further inland feature rolling hills and temperate forests. The [[Appalachian Mountains]] form a line of low mountains separating the eastern seaboard from the Great Lakes and the Mississippi Basin. The five [[Great Lakes]] are located in the north-central portion of the country, four of them forming part of the border with [[Canada]]. The southeast United States contain subtropical forests and, near the gulf coast, [[mangrove]] wetlands, especially in [[Florida]]. West of the Appalachians lies the [[Mississippi River]] basin and two large eastern tributaries, the [[Ohio River]] and the [[Tennessee River]]. The [[Ohio Valley|Ohio]] and [[Tennessee Valley|Tennessee]] Valleys and the [[Midwestern U.S.|Midwest]] consist largely of rolling hills and productive farmland, stretching south to the [[U.S. Gulf Coast|Gulf Coast]].
The [[Great Plains]] lie west of the Mississippi River and east of the Rocky Mountains. A large portion of the country's agricultural products are grown in the Great Plains. Before their general conversion to farmland, the Great Plains were noted for their extensive grasslands, from [[tallgrass prairie]] in the eastern plains to [[shortgrass prairie|shortgrass steppe]] in the western [[High Plains]]. Elevation rises gradually from less than a few hundred feet near the Mississippi River to more than a mile high in the High Plains. The generally low relief of the plains is broken in several places, most notably in the [[The Ozarks|Ozark]] and [[Ouachita Mountains]], which form the [[U.S. Interior Highlands]], the only major mountainous region between the [[Rocky Mountains]] and the [[Appalachian Mountains]].<ref>{{cite web | url=http://www.srs.fs.usda.gov/4106/about/HotSpringsOffice.htm | title= Managing Upland Forests of the Midsouth| publisher= United States Forestry Service | accessdate=2007-10-13}}</ref><ref>{{cite web | url=http://tapestry.usgs.gov/physiogr/physio.html| title= A Tapestry of Time and Terrain: The Union of Two Maps - Geology and Topography| publisher= United States Geological Survey | accessdate=2007-10-13}}</ref>
The Great Plains come to an abrupt end at the [[Rocky Mountains]]. The Rocky Mountains form a large portion of the [[Western U.S.]], entering from [[Canada]] and stretching nearly to [[Mexico]]. The Rocky Mountains generally contain fairly mild slopes and low peaks compared to many of the other great mountain ranges, with a few exceptions (such as the [[Teton Mountains]] in [[Wyoming]] and the [[Sawatch Range]] in [[Colorado]]). In addition, instead of being one generally continuous and solid mountain range, it is broken up into a number of smaller, intermittent mountain ranges, forming a large series of basins and valleys.
West of the Rocky Mountains lies the [[Intermontane Plateaus]] (also known as the [[Intermountain West]]), a large, arid desert lying between the Rockies and the [[Cascade Range|Cascades]] and [[Sierra Nevada (U.S.)|Sierra Nevada]] ranges. The large southern portion, known as the [[Great Basin]], consists of salt flats, drainage basins, and many small north-south mountain ranges. The [[Southwestern United States|Southwest]] is predominantly a low-lying desert region. A portion known as the [[Colorado Plateau]], centered around the [[Four Corners]] region, is considered to have some of the most spectacular scenery in the world. It is accentuated in such national parks as [[Grand Canyon National Park|Grand Canyon]], [[Arches National Park|Arches]], and [[Bryce Canyon National Park|Bryce Canyon]], among others.
[[Image:Grand Canyon from Moran Point.jpeg|thumb|right|[[The Grand Canyon]] from Moran Point. The Grand Canyon is among the most famous locations in the country.]]
The Intermontane Plateaus come to an end at the [[Cascade Range]] and the [[Sierra Nevada (U.S.)|Sierra Nevada]]. The Cascades consist of largely intermittent, volcanic mountains rising prominently from the surrounding landscape. The Sierra Nevada, further south, is a high, rugged, and dense mountain range. It contains the highest point in the contiguous 48 states, [[Mount Whitney]] (14,505 ft; 4,421 m). These areas contain some spectacular scenery as well, as evidenced by such national parks as [[Yosemite National Park|Yosemite]] and [[Mount Rainier National Park|Mount Rainier]]. West of the Cascades and Sierra Nevada is a series of valleys, such as the [[Central Valley (California)|Central Valley]] in [[California]] and the [[Willamette Valley]] in [[Oregon]]. Along the coast is a series of low mountain ranges known as the [[Pacific Coast Ranges]]. Much of the [[Pacific Northwest]] coast is inhabited by some of the densest vegetation outside of the [[Tropics]], and also the tallest trees in the world (the [[Coast Redwood|Redwoods]]).
[[Alaska]] contains some of the most dramatic and untapped scenery in the country. Tall, prominent mountain ranges rise up sharply from broad, flat tundra plains. On the islands off the south and southwest coast are many [[volcanoes]]. [[Hawaii]], far to the south of [[Alaska]] in the [[Pacific Ocean]], is a chain of tropical, volcanic islands, popular as a tourist destination for many from [[East Asia]] and the mainland United States.
The geography of the United States varies across their immense area. Within the contential U.S., [[Physiographic Regions of the United States|eight distinct physiographic divisions]] exist, though each is composed of several smaller physiographic subdivisions.<ref>{{cite web | title = Physiographic Regions | publisher = [[United States Geological Survey]] | date = [[2003-04-17]] | url = http://tapestry.usgs.gov/physiogr/physio.html | accessdate = 2008-01-30 }}</ref> These major divisions are:
* [[Laurentian Upland]] - part of the [[Canadian Shield]] that extends into the northern United States [[Great Lakes (North America)|Great Lakes]] area.
* [[Atlantic Plain]] - the coastal regions of the eastern and southern parts includes the continental shelf, the [[East Coast of the United States|Atlantic Coast]] and the [[U.S. Gulf Coast|Gulf Coast]].
* [[Appalachian Highlands]] - lying on the eastern side of the United States, it includes the [[Appalachian Mountains]], [[Adirondacks]] and [[New England]] province.
* [[Interior Plains]] - part of the interior contentintal United States, it includes much of what is called the [[Great Plains]].
* [[Interior Highlands]] - also part of the interior contentintal United States, this division includes the [[Ozark]] Plateau.
* [[Geography of the United States Rocky Mountain System|Rocky Mountain System]] - one branch of the [[American cordillera|Cordilleran]] system lying far inland in the western states.
* [[Geography of the United States Intermontane Plateaus|Intermontane Plateaus]] - also divided into the [[Columbia Plateau]], the [[Colorado Plateau]] and the [[Basin and Range Province]], it is a system of plateaus, basins, ranges and gorges between the Rocky and Pacific Mountain Systems. It is the setting for the [[Grand Canyon]], the [[Great Basin]] and [[Death Valley]].
* [[Geography of the United States Pacific Mountain System|Pacific Mountain System]] - the coastal mountain ranges and features in the [[West Coast of the United States|west coast of the United States]].
[[Image:arch.usa.arp.750pix.jpg|thumb|left|250px|Delicate Arch, [[Arches National Park]], Utah]]The Atlantic coast of the United States is, with minor exceptions, low. The Appalachian Highland owes its oblique northeast-southwest trend to crustal deformations which in very early geological time gave a beginning to what later came to be the Appalachian mountain system. This system had its climax of deformation so long ago (probably in [[Permian]] time) that it has since then been very generally reduced to moderate or low relief. It owes its present day altitude either to renewed elevations along the earlier lines or to the survival of the most resistant rocks as residual mountains. The oblique trend of this coast would be even more pronounced but for a comparatively modern crustal movement, causing a depression in the northeast resulting in an encroachment of the sea upon the land. Additionally, the southeastern section has undergone an elevation resulting in the advance of the land upon the sea.
The following map, known as a [[physiography|physiographical]] map, shows [[geography|geographical]] and [[terrain]] information about the regions of the contiguous 48 states of the U.S. used by [[earth science|earth scientists]]. The map indicates the age of the exposed surface as well as the type of terrain. More information about the regions is covered in several sub articles found in the additional topics subsection below.
[[Image:US physiographic map.jpg|thumb|right|[[Physiographic Regions of the United States]].]]
While the Atlantic coast is relatively low, the Pacific coast is, with few exceptions, hilly or mountainous. This coast has been defined chiefly by geologically recent crustal deformations, and hence still preserves a greater relief than that of the Atlantic.
The low Atlantic coast and the hilly or mountainous Pacific coast foreshadow the leading features in the distribution of mountains within the United States. The east coast Appalachian system, originally forest covered, is relatively low and narrow and is bordered on the southeast and south by an important coastal plain. The [[American cordillera|Cordilleran system]] on the western side of the continent is lofty, broad and complicated having two branches, the Rocky Mountain System and the Pacific Mountain System. In between these, lie the Intermontaine Plateaus. Heavy forests cover the northwest coast, but elsewhere trees are found only on the higher ranges below the Alpine region. The [[intermontane]] valleys, plateaus and basins range from treeless to desert with the very arid region being in the
southwest.
Both the [[Columbia River]] and [[Colorado River]] rise far inland near the easternmost members of the Cordilleran system, and flow through plateaus and intermontaine basins to the ocean.
The Laurentian Highlands, the Interior Plains and the Interior Highlands lie between the two coasts, stretching from the [[Gulf of Mexico]] northward, far beyond the national boundary, to the [[Arctic Ocean]]. The central plains are divided by a hardly perceptible height of land into a [[Canada|Canadian]] and a United States portion. It is from the United States side, that the great [[Mississippi River|Mississippi]] system discharges southward to the Gulf of Mexico. The upper Mississippi and some of the [[Ohio River|Ohio]] basin is the semi-arid prairie region, with trees originally only along the watercourses. The uplands towards the Appalachians were included in the great eastern forested area, while the western part of the plains has so dry a climate that its native plant life is scanty, and in the south it is practically barren.
See also: [[List of North American deserts]]
Elevation extremes:
*Lowest point: [[Death Valley]], [[Inyo County, California]] 282 feet below [[sea level]] (-86 m)
*Highest point: [[Mount McKinley]], [[Denali Borough, Alaska]] 20,320 feet above sea level (+6,194 m)
== Climate ==
{{main|Climate of the United States}}
[[Image:Verybroadclimatemap.png|thumb|240px|right|Climate zones of the lower 48 United States.]]
[[Image:Average precipitation in the lower 48 states of the USA.png|thumb|right|Average precipitation]]
Due to its large size and wide range of geographic features, the United States contains examples of nearly every global climate. The climate is temperate in most areas, tropical in [[Hawaii]] and southern [[Florida]], polar in [[Alaska]], semiarid in the [[Great Plains]] west of the [[100th meridian west|100th meridian]], Mediterranean in coastal [[California]] and arid in the [[Great Basin]]. Its comparatively generous climate contributed (in part) to the country's rise as a world power, with infrequent severe drought in the major agricultural regions, a general lack of widespread flooding, and a mainly temperate climate that receives adequate precipitation.
[[Image:Prospect Heights Blizzard NYC 2-12-06.jpg|left|thumb|Deep snow during the [[North American blizzard of 2006|Blizzard of 2006]] [[Nor'easter]] in [[Brooklyn]], [[New York City]].]]
The main influence on U.S. weather is the [[jet stream|polar jet stream]], which brings in large low pressure systems from the northern [[Pacific Ocean]]. The [[Cascade Range]], [[Sierra Nevada (U.S.)|Sierra Nevada]], and [[Rocky Mountains]] pick up most of the moisture from these systems as they move eastward. Greatly diminished by the time they reach the [[High Plains (United States)|High Plains]], much of the moisture has been sapped by the [[Precipitation (meteorology)#Orographic precipitation|orographic effect]] as it is forced over several mountain ranges. However, once it moves over the [[Great Plains]], uninterrupted flat land allows it to reorganize and can lead to major clashes of air masses. In addition, moisture from the [[Gulf of Mexico]] is often drawn northward. When combined with a powerful jet stream, this can lead to violent thunderstorms, especially during spring and summer. Sometimes during late winter and spring these storms can combine with another low pressure system as they move up the East Coast and into the [[Atlantic Ocean]], where they intensify rapidly. These storms are known as Nor'easters and often bring widespread, heavy snowfall to the [[Mid-Atlantic States|Mid-Atlantic]] and [[New England]]. The uninterrupted flat grasslands of the [[Great Plains]] also leads to some of the most extreme climate swings in the world. Temperatures can rise or drop rapidly and winds can be extreme, and the flow of heat waves or Arctic air masses often advance uninterrupted through the plains.
[[Image:SunsetBeach.jpg|thumb|right|The U.S. State of [[Hawaii]] has a year-round [[tropical climate]], and is known for its many beaches, such as this one on [[O'ahu]].]]
The [[Great Basin]] and [[Columbia Plateau]] (the [[Intermontane Plateaus]]) are arid or semiarid regions that lie in the rain shadow of the [[Cascade Mountains|Cascades]] and [[Sierra Nevada (U.S.)|Sierra Nevada]]. Precipitation averages less than 15 [[inch]]es (38 cm). The [[Southwestern U.S.|Southwest]] is a hot desert, with temperatures exceeding 100°F (38°C) for several weeks at a time in summer. The Southwest and the Great Basin are also affected by the [[monsoon]] from the [[Gulf of California]] from July-September, which brings localized but often severe thunderstorms to the region.
[[Image:Comparison Size with United States map.GIF|thumb|Right|Size comparisons between the contiguous United States and other world geographic bodies]]
Much of [[California]] consists of a [[Mediterranean climate]], with sometimes excessive rainfall from October-April and nearly no rain the rest of the year. In the [[Pacific Northwest]] rain falls year-round, but is much heavier during winter and spring. The mountains of the west receive abundant precipitation and very heavy snowfall. The Cascades are one of the snowiest places in the world, with some places averaging over 600 inches (1,520 cm) of snow annually, but the lower elevations closer to the coast receive very little snow. Another significant (but localized) weather effect is [[lake-effect snow]] that falls south and east of the [[Great Lakes]], especially in the hilly portions of the [[Upper Peninsula]] of [[Michigan]] and on the [[Tug Hill Plateau]] in [[New York]].The lake effect dumped well over 5 feet of snow in the Buffalo, New York area throughout the 2006-2007 winter The [[Wasatch Front]] and [[Wasatch Range]] in [[Utah]] can also receive significant lake effect accumulations off of the [[Great Salt Lake]].
===Extremes===
In northern Alaska, [[tundra]] and [[arctic]] conditions predominate, and the temperature has fallen as low as minus 80 °[[Fahrenheit|F]] (−62 °[[Celsius|C]]).<ref>Williams, Jack [http://www.usatoday.com/weather/wcstates.htm Each state's low temperature record], ''USA today'', ''URL accessed 13 June, 2006.''</ref> On the other end of the spectrum, [[Death Valley National Park|Death Valley, California]] once reached 134 °F (56.7 °C), the second-highest temperature ever recorded on Earth.<ref name="Death_Valley">{{cite web | url = http://www.nps.gov/deva/planyourvisit/upload/Weather.pdf | title = Weather and Climate | accessmonthday = October 5 | accessyear = 2006 | year = 2002 | month = January | format = PDF | work = Official website for Death Valley National Park | publisher = National Park Service U. S. Department of the Interior | pages = 1-2}}</ref>
On average, the mountains of the western states receive the highest levels of snowfall on Earth. The greatest annual snowfall level is at [[Mount Rainier]] in [[Washington]], at 692 [[inch]]es (17,580 mm); the record there was 1,122 inches (28,500 mm) in the winter of 1971–72. This record was broken by the Mt. Baker Ski Area in northwestern Washington which reported 1,140 inches of snowfall for the 1998-99 snowfall season. Other places with significant snowfall outside the Cascade Range are the [[Wasatch Mountains]], near the [[Great Salt Lake]], and the [[Sierra Nevada (U.S.)|Sierra Nevada]], near [[Lake Tahoe]]. In the east, while snowfall does not approach western levels, the region near the Great Lakes and the mountains of the Northeast receive the most. Along the northwestern Pacific coast, rainfall is greater than anywhere else in the continental U.S., with [[Quinault Ranger]] in Washington having an average of 137 inches (3480 mm).<ref>National Atlas, [http://www.nationalatlas.gov/mld/prism0p.html Average Annual Precipitation, 1961-1990], ''URL accessed 15 June 2006.''</ref> Hawaii receives even more, with 460 inches (11,680 mm) measured annually on [[Mount Waialeale]], in [[Kauai]]. The [[Mojave Desert]], in the southwest, is home to the driest locale in the U.S. [[Yuma, Arizona]], has an average of 2.63 inches (66.8 mm) of [[precipitation (meteorology)|precipitation]] each year.<ref>Hereford, Richard, et al, [http://pubs.usgs.gov/fs/fs117-03/ Precipitation History of the Mojave Desert Region, 1893–2001], ''U.S. Geological Survey, Fact Sheet 117-03'', ''URL accessed 13 June 2006.''</ref>
In central portions of the U.S., [[tornado]]es are more common than anywhere else on Earth<ref>NOVA, [http://www.pbs.org/wgbh/nova/tornado/country.html Tornado Heaven], ''Hunt for the Supertwister'', ''URL accessed 15 June 2006.''</ref> and touch down most commonly in the spring and summer. Deadly and destructive [[hurricane]]s occur almost every year along the Atlantic seaboard and the Gulf of Mexico. The Appalachian region and the Midwest experience the worst floods, though virtually no area in the U.S. is immune to flooding. The Southwest has the worst droughts; one is thought to have lasted over 500 years and to have decimated the [[Anasazi]] people.<ref>O'Connor, Jim E. and John E. Costa, [http://pubs.usgs.gov/circ/2003/circ1245/ Large Floods in the United States: Where They Happen and Why], ''U.S. Geological Survey Circular 1245'', ''URL accessed 13 June 2006.''</ref> The West is affected by large wildfires each year.
==Natural disasters==
The United States is affected by a large variety of natural disasters yearly. Although severe drought is rare, it has occasionally caused major problems, such as during the [[Dust Bowl]] (1931-1942), which coincided with the [[Great Depression]]. Farmland failed throughout the Plains, entire regions were virtually depopulated, and dust storms ravaged the land. More recently, the western U.S. experienced widespread drought from 1999-2004, and signs of a major, long-term drought across the [[Great Plains]] have developed.[http://wwwa.accuweather.com/promotion.asp?dir=aw&page=dustbowl] In the past year, drought has spread from the Southern Plains westward through the Southwest and east along the Gulf Coast to Florida.
[[Image:Dimmitt Tornado1 - NOAA.jpg|thumb|left|A powerful tornado in Texas]]
The United States also experience, by a large margin, the most frequent and powerful [[tornado]]es in the world. The Great Plains and Midwest, due to the contrasting air masses, sees frequent severe thunderstorms and tornado outbreaks during spring and summer. The strip of land from north [[Texas]] north to [[Kansas]] and east into [[Tennessee]] is known as [[Tornado Alley]], where many houses have tornado shelters and many towns have tornado sirens. Another natural disaster that frequents the country are [[hurricane]]s, which can hit anywhere along the [[U.S. Gulf Coast|Gulf Coast]] or the [[Atlantic Coast]] as well as [[Hawaii]] in the [[Pacific Ocean]]. Particularly at risk are the central and southern [[Texas]] coasts, the area from southeastern [[Louisiana]] east to the [[Florida Panhandle]], the east coast of [[Florida]], and the [[Outer Banks]] of [[North Carolina]], although any portion of the coast could be struck. Hurricane season runs from [[June 1]] to [[November 30]], with a peak from mid-August through early October. Some of the more devastating hurricanes have included the [[Galveston Hurricane of 1900]], [[Hurricane Andrew]] in 1992, and [[Hurricane Katrina]] in 2005. The remnants of tropical cyclones from the Eastern Pacific also occasionally impact the southwestern United States, bringing sometimes heavy rainfall.
[[Image:Hurricane katrina damage gulfport mississippi.jpg|thumb|right|Total devastation in [[Gulfport, Mississippi]] following [[Hurricane Katrina]] in 2005.]]
Like drought, widespread severe flooding is rare. Some exceptions include the [[Great Mississippi Flood of 1927]], the [[Great Flood of 1993]], and widespread flooding and mudslides caused by the 1982-1983 [[ENSO|El Niño]] event in the western United States. Localized flooding can, however, occur anywhere, and mudslides from heavy rain can cause problems in any mountainous area, particularly the Southwest. Large stretches of desert shrub in the west can fuel the spread of [[wildfire]]s. The narrow canyons of many mountain areas in the west and severe thunderstorm activity during the [[monsoon]] season in summer leads to sometimes devastating [[flash flood]]s as well, while Nor'Easter snowstorms can bring activity to a halt throughout the Northeast (although heavy snowstorms can occur almost anywhere).
The West Coast of the continental United States and areas of Alaska (including the [[Aleutian Islands]], the [[Alaskan Peninsula]] and southern Alaskan coast) make up part of the [[Pacific Ring of Fire]], an area of heavy tectonic and volcanic activity that is the source of 90% of the world's earthquakes. The American Northwest sees the highest concentration of active volcanoes in the United States, in [[Washington]], [[Oregon]] and [[northern California]] along the [[Cascade Mountains]]. There are several active volcanoes located in the islands of [[Hawaii]], including Kilauea in ongoing eruption since 1983, but they do not typically adversely affect the inhabitants of the islands. There has not been a major life-threatening eruption on the Hawaiian islands since the 17th century. Volcanic eruptions can occasionally be devastating, such as in the [[1980 eruption of Mount St. Helens]] in Washington.
The Ring of Fire makes [[California]] and southern [[Alaska]] particularly vulnerable to [[earthquake]]s. Earthquakes can cause extensive damage, such as the [[1906 San Francisco Earthquake]] or the 1964 [[Good Friday Earthquake]] near [[Anchorage, Alaska]]. California is well known for seismic activity, and requires large structures to be [[earthquake resistant]] to minimize loss of life and property. Outside of devastating earthquakes, California experiences minor earthquakes on a regular basis.
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; and on occasion a terrorist attack.
==Public lands==
The United States holds many areas for the use and enjoyment of the public. These include [[national park|National Parks]], [[United States National Monument|National Monuments]], [[National Forest]]s, [[Wilderness area]]s, and other areas. For lists of areas, see the following articles:
*[[List of U.S. National Parks]]
*[[List of U.S. National Forests]]
*[[List of U.S. wilderness areas]]
*[[List of miscellaneous U.S. public areas]]
==See also==
*[[Counties of the United States]]
*[[Extreme points of the United States]]
*[[Geographic centers of the United States]]
*[[Geography of Puerto Rico]]
*[[Geography of the Eastern United States]]
*[[Geography of the Interior United States]]
*[[Geography of the Western United States]]
*[[Historic regions of the United States]]
*[[List of islands of the United States]]
*[[List of mountains of the United States]]
*[[List of North American deserts]]
*[[List of US government designations for places]]
*[[Mountain peaks of the United States]]
*[[Public Land Survey System]]
*[[Regions of the United States]]
*[[Territorial evolution of the United States]]
*[[Russia-United States maritime boundary]]
==References==
{{reflist|1}}
==External links==
{{commonscat}}
*[http://tapestry.usgs.gov USGS: Tapestry of Time and Terrain]
*[http://www.usgs.gov/ United States Geological Survey] - Maintains free aerial maps
*[http://www.nationalatlas.gov/ National Atlas of the United States of America]
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[[de:Geographie der Vereinigten Staaten]]
[[es:Geografía de Estados Unidos]]
[[fr:Géographie des États-Unis d'Amérique]]
[[id:Geografi Amerika Serikat]]
[[it:Geografia degli Stati Uniti d'America]]
[[lt:JAV geografija]]
[[pt:Geografia dos Estados Unidos da América]]
[[ro:Geografia Statelor Unite ale Americii]]
[[ru:География США]]
[[sk:Geografia USA]]
[[sl:Geografija Združenih držav Amerike]]
[[sv:USA:s geografi]]
[[vi:Địa lý Hoa Kỳ]]
[[zh:美国地理]]