Three major mountain ranges
· Appalachian Mountains
· Coastal Ranges
· Sierra Nevada
The Appalachian Mountains are mostly located in the United States but extends into southeastern Canada, forming a zone from 100 to 300 mi (160 to 480 km) wide, running from the island of Newfoundland 1,500 mi (2,400 km) south-westward to Central Alabama in the United States. The system is divided into a series of ranges, with the individual mountains averaging around 3,000 ft (910 m). The highest of the group is Mount Mitchell in North Carolina at 6,684 feet (2,037 m), which is the highest point in the United States east of the Mississippi River.
The term Appalachian refers to several different regions associated with the mountain range. Most broadly, it refers to the entire mountain range with its surrounding hills and the dissected plateau region. However, the term is often used more restrictively to refer to regions in the central and southern Appalachian Mountains, usually including areas in the states of Kentucky, Tennessee, Virginia, Maryland, West Virginia, and North Carolina, as well as sometimes extending as far south as northern Georgia and western South Carolina, as far north as Pennsylvania and southern Ohio.
The Ouachita Mountains in Arkansas and Oklahoma were originally part of the Appalachians as well, but became disconnected through geologic history.
The Coast Mountains are a major mountain range, in the Pacific Coast Ranges, of western North America, extending from southwestern Yukon through the Alaska Panhandle and virtually all of the Coast of British Columbia. They are so-named because of their proximity to the sea coast, and are often referred to as the Coast Range. It includes volcanic and non-volcanic mountains and the huge icefields of the Pacific and Boundary Ranges, and the northern end of the notable volcanic system known as the Cascade Volcanoes. The Coast Mountains are part of a larger mountain system called the Pacific Coast Ranges or the Pacific Mountain System, which includes the Cascade Range, the Insular Mountains, the Oregon and California Coast Ranges and the Saint Elias and Chugach Mountains.
The Coast Mountains are approximately 1,600 kilometres (990 mi) long and average 300 kilometres (190 mi) in width. Its southern and southeastern boundaries are surrounded by the Fraser River and the Interior Plateau while its far northwestern edge is delimited by the Kelsall and Tatshenshini Rivers at the north end of the Alaska Panhandle, beyond which are the Saint Elias Mountains, and by Champagne Pass in the Yukon Territory. Covered in dense temperate rainforest on its western exposures, the range rises to heavily glaciated peaks, including the largest temperate-latitude icefields in the world. It then tapers to the dry Interior Plateau on its eastern flanks, or to the subarctic boreal forest of the Skeena Mountains and Stikine Plateau.
The Coast Mountains are part of the Pacific Ring of Fire, the ring of volcanoes and associated mountains around the Pacific Ocean. It contains some of British Columbia's highest mountains. Mount Waddington, northeast of the head of Knight Inlet with an elevation of 4,019 metres (13,186 ft), is the highest mountain of the Coast Mountains and the highest that lies entirely within British Columbia.
American National Parks
Acadia National Park is a National Park located in the U.S. state of Maine. It reserves much of Mount Desert Island, and associated smaller islands, off the Atlantic coast. Originally created as Lafayette National Park in 1919, the first National Park East of the Mississippi, it was renamed Acadia in 1929.
The park includes mountains, an ocean shoreline, woodlands, and lakes. In addition to Mount Desert Island, the park comprises much of the Isle au Haut, parts of Baker Island, and a portion of the Schoodic Peninsula on the mainland.
In total, Acadia National Park consists of more than 47,000 acres (73 square miles, 190 km2), including 30,300 acres (47 sq mi., 123 km2) on Mount Desert Island, 2,728 acres (4.6 sq mi., 11 km2) on Isle au Haut and 2,366 acres (3.5 sq mi., 9.2 km2) on the Schoodic Peninsula.
Cadillac Mountain, named after the French Explorer of the same name, is on the eastern side of the island. Its green, lichen-covered, pink granite summit is, because of a combination of its eastern location and height, one of the first places in the United States to see the sunrise. Miles of carriage roads were originally built by John D. Rockefeller, Jr. The mountains of Acadia National Park offer hikers and bicycle riders views of the ocean, island lakes, and pine forests.
The inlet Somes Sound, often described as the "only fjord on the East Coast", is now called a fjard by officials.
The park is home to some 40 different species of mammalian wildlife. Among these are red and gray squirrels, chipmunks, white-tailed deer, moose, beaver (Castor canadensis), porcupine, muskrats, foxes, coyote, bobcats, and black bears. Many other marine species have been observed in the surrounding area and waters.
Excavations of old Indian sites in the Mount Desert Island region have yielded remains of the native mammals. Bones of wolf, beaver, deer, elk, Gray seal (Halichoerus grypus), the Indian dog, and Sea Mink (Neovison macrodon), as well as large numbers of raccoon, lynx, wolf, muskrat, and deer. Although beaver were trapped to extinction on the island, two pairs of beaver that were released in 1920 by George B. Dorr at the brook between Bubble Pond and Eagle Lake have repopulated it. The large fire in 1947 cleared the eastern half of the island of its coniferous trees and permitted the growth of aspen, birch, alder, maple and other deciduous trees which enabled the beaver to thrive.
Species that used to inhabit the island include the mountain lion (or puma) and the gray wolf. It is thought that these predators have been forced to leave the area due to the dramatic decrease in small prey and proximity to human activity.
Dry Tortugas National Park preserves Fort Jefferson and the Dry Tortugas section of the Florida Keys. The park covers 101 mi2(262 km2), mostly water, about 68 statute miles (109 km) west of Key West in the Gulf of Mexico.
It is famous for abundant sea life, colorful coral reefs and legends of shipwrecks and sunken treasures. The park's centerpiece is Fort Jefferson, a massive but unfinished coastal fortress. It is the largest masonry structure in the Western Hemisphere, and is composed of over 16 million bricks. The park has almost 80,000 visitors each year. The park is accessible only by seaplane or boat. Ferries leave from Key West. Activities include snorkeling, picnicking, camping, scuba diving, saltwater fishing and birdwatching.
Dry Tortugas National Park has an official bird list of 299 species. Of these, only seven species frequently nest within the park: Sooty Tern, Brown Noddy, Brown Pelican, Magnificent Frigatebird, Masked Booby, Roseate Tern, and Mourning Dove.
Birdwatching activity peaks each spring (usually April) when dozens of migratory bird species can pass through the park in a single day. Many birds land inside the parade grounds of Fort Jefferson where they are often observed at close range. Several species of falcon as well as Cattle Egrets are often seen hunting songbirds. A small freshwater fountain beneath Buttonwood trees represents the only freshwater source for many miles, and is a popular spot to watch migrant birds. Each year several bird guides offer tours of Dry Tortugas National Park during April and early May.
Another popular spectacle is the Sooty Tern nesting season on Bush Key between February and September, which involves an approximately 80,000 terns. Bush Key remains closed to visitors during the nesting season, but bird watchers with binoculars or telephoto lenses can watch the spectacle from Fort Jefferson.
Rocky Mountain National Park is a national park located in the north-central region of the U.S. state of Colorado. It features majestic mountain views, a variety of wildlife, varied climates and environments—from wooded forests to mountain tundra—and easy access to back-country trails and campsites. The park is located northwest of Boulder, Colorado, in the Rockies, and includes the Continental Divide and the headwaters of the Colorado River.
The park has five visitor centers. The park headquarters, Beaver Meadows Visitor Center, is a National Historic Landmark, designed by the Frank Lloyd Wright School of Architecture at Taliesin West.
The park may be accessed by three roads: U.S. Highway 34, 36, and State Highway 7. Highway 7 enters the park for less than a mile, where it provides access to the Lily Lake Visitor Center which is closed indefinitely. Farther south, spurs from route 7 lead to campgrounds and trail heads around Longs Peak and Wild Basin. Highway 36 enters the park on the east side, where it terminates after a few miles at Highway 34. Highway 34, known as Trail Ridge Road through the park, runs from the town of Estes Park on the east to Grand Lake on the southwest. The road reaches an elevation of 12,183 feet (3,713 m), and is closed by snow in winter.
The California Zephyr serves Granby (near the west entrance of the park) by rail from Denver, crossing the Continental Divide through the Moffat Tunnel well south of the park. The park's website suggests Granby as an appropriate rail terminus for visitors, although it lies a good sixteen miles from the park without public transportation connections.
The park is surrounded by Roosevelt National Forest on the north and east, Routt National Forest on the northwest, and Arapaho National Forest on the southwest.
New Yorkis the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and entertainment. The home of the United Nations Headquarters, New York is an important center for international diplomacy and has been described as the cultural capital of the world. The city is also referred to as New York City or the City of New York to distinguish it from the state of New York, of which it is a part.
Located on one of the world's largest natural harbors, New York City consists of five boroughs, each of which comprises a state county. The five boroughs — The Bronx, Brooklyn, Manhattan, Queens, and Staten Island — were consolidated into a single city in 1898. With a 2010 United States Census population of 8,175,133 distributed over a land area of just 305 square miles (790 km2), York is the most densely populated major city in the United States. As many as 800 languages are spoken in New York, making it the most linguistically diverse city in the world. The New York City Metropolitan Area's population is the United States' largest, estimated at 18.9 million people distributed over 6,720 square miles (17,400 km2), and is also part of the most populous combined statistical area in the United States, containing 22.2 million people as of 2009 Census estimates.
New York traces its roots to its 1624 founding as a trading post by colonists of the Dutch Republic, and was named New Amsterdam in 1626. The city and its surrounds came under English control in 1664 and were renamed New York after King Charles II of England granted the lands to his brother, the Duke of York. New York served as the capital of the United States from 1785 until 1790. It has been the country's largest city since 1790. The Statue of Liberty greeted millions of immigrants as they came to America by ship in the late 19th and early 20th centuries and is a globally recognized symbol of the United States and its democracy.
Many districts and landmarks in New York City have become well known to its approximately 50 million annual visitors. Times Square, iconified as "The Crossroads of the World", is the brightly illuminated hub of the Broadway theater district, one of the world's busiest pedestrian intersections, and a major center of the world's entertainment industry. The city hosts many world renowned bridges, skyscrapers, and parks. New York City's financial district, anchored by Wall Street in Lower Manhattan, functions as the financial capital of the world and is home to the New York Stock Exchange, the world's largest stock exchange by total market capitalization of its listed companies. Manhattan's real estate market is among the most expensive in the world. Manhattan's Chinatown incorporates the highest concentration of Chinese people in the Western Hemisphere. Providing continuous 24/7 service, the New York City Subway is one of the most extensive rapid transit systems in the world. Numerous colleges and universities are located in New York, including Columbia University, New York University, and Rockefeller University, which are ranked among the top 50 in the world.
Los Angeles ( 
i/lɒs ˈændʒələs/ loss-AN-jə-ləs; Spanish: [los ˈaŋxeles]), with a population at the 2010 United States Census of 3,792,621, is the most populous city in the state of California, and the second most populous in the United States, after New York City. It has an area of 468.67 square miles (1,213.8 km2), and is located in Southern California. Often known by its initials L.A., the city is the focal point of the larger Los Angeles-Long Beach-Santa Ana metropolitan statistical area, which contains 12,828,837 people as of 2010, and is one of the most populous metropolitan areas in the world and the second largest in the United States. Los Angeles is also the seat of Los Angeles County, the most populated and one of the most ethnically diverse counties in the United States, while the entire Los Angeles area itself has been recognized as the most diverse of the nation's largest cities. The city's inhabitants are referred to as "Angelenos".
Los Angeles was founded on September 4, 1781, by Spanish governor Felipe de Neve. It became a part of Mexico in 1821 following the Mexican War of Independence. In 1848, at the end of the Mexican–American War, Los Angeles and the rest of California were purchased as part of the Treaty of Guadalupe Hidalgo, thereby becoming part of the United States. Los Angeles was incorporated as a municipality on April 4, 1850, five months before California achieved statehood.
Nicknamed the City of Angels, Los Angeles is a world center of business, international trade, entertainment, culture, media, fashion, science, sports, technology, and education. It is home to renowned institutions covering a broad range of professional and cultural fields and is one of the most substantial economic engines within the United States. Los Angeles has been ranked the third richest city and fifth most powerful and influential city in the world.The Los Angeles combined statistical area (CSA) has a gross metropolitan product (GMP) of $831 billion (as of 2008), making it the third largest economic center in the world, after the Greater Tokyo and New York metropolitan areas. As the home base of Hollywood, it is also known as the "Entertainment Capital of the World," leading the world in the creation of television and stage production, motion pictures, video games, and recorded music. The importance of the entertainment business to the city has led many celebrities to call Los Angeles and its surrounding suburbs home. Additionally, Los Angeles hosted the 1932 and 1984 Summer Olympics.
Chicago ( i/ʃɪˈkɑːɡoʊ/ or /ʃɪˈkɔːɡoʊ/) is the largest city in the U.S. State (606.1km square) of Illinois and the third most populous city in the United States, with around 2.7 million residents. Its metropolitan area, sometimes called "Chicagoland," is the third largest in the United States, with an estimated 9.8 million people in the states of Illinois, Wisconsin and Indiana. Chicago is the county seat of Cook County.
Chicago was incorporated as a town in 1833, near a portage between the Great Lakes and the Mississippi River watershed.Today, the city retains its status as a major hub for industry, telecommunications and infrastructure, with O'Hare International Airport being the second busiest airport in the world in terms of traffic movements. In 2008[update], the city hosted 45.6 million domestic and overseas visitors. Among metropolitan areas, the Chicago area has the 4th largest Gross Domestic Product (GDP) in the world. Chicago is an important worldwide center of commerce.
The city's notoriety has found expression in numerous forms of popular culture, including novels, plays, movies, songs, various types of journals (for example, sports, entertainment, business, trade, and academic), and the news media. Chicago has many nicknames, which reflect the impressions and opinions about historical and contemporary Chicago. The best known include: "Chi-town," "Windy City," "Second City,"[footnote 1] and the "City of Big Shoulders."[footnote 2]
Houston ( 
/ˈhjuːstən/) is the largest city in the state of Texas, and the fourth-largest city in the United States. According to the 2010 U.S. Census, the city had a population of 2.1 million people within an area of 579 square miles (1,500 km2). Houston is the seat of Harris County and the economic center of Houston–Sugar Land–Baytown, which is the sixth-largest metropolitan area in the United States, with nearly 6 million people.
Houston, known as the Bayou City, was founded in 1836 on land near the banks of Buffalo Bayou. It was incorporated as a city on June 5, 1837, and named after then-President of the Republic of Texas—former General Sam Houston—who had commanded at the Battle of San Jacinto, which took place 25 miles (40 km) east of where the city was established. The burgeoning port and railroad industry, combined with oil discovery in 1901, has induced continual surges in the city's population. In the mid-twentieth century, Houston became the home of the Texas Medical Center—the world's largest concentration of healthcare and research institutions—and NASA's Johnson Space Center, where the Mission Control Center is located.
Rated as a global city, Houston's economy has a broad industrial base in energy, manufacturing, aeronautics, and transportation. It is also leading in health care sectors and building oilfield equipment; only New York City is home to more Fortune 500 headquarters. The Port of Houston ranks first in the United States in international waterborne tonnage handled and second in total cargo tonnage handled. The city has a population from various ethnic and religious backgrounds and a large and growing international community. It is home to many cultural institutions and exhibits, which attract more than 7 million visitors a year to the Museum District. Houston has an active visual and performing arts scene in the Theater District and offers year-round resident companies in all major performing arts.
Philadelphia ( /ˌfɪləˈdɛlfiə/) is the largest city in the Commonwealth of Pennsylvania and the county seat of Philadelphia County, with which it is coterminous. The city is located in the Northeastern United States along the Delaware and Schuylkill rivers. It is the fifth-most-populous city in the United States, with a population of 1,526,006 as of the 2010 U.S. Census. Philadelphia is also the commercial, cultural, and educational center of the Delaware Valley, home to 6 million people and the country's fifth-largest metropolitan area. The Philadelphia metropolitan division consists of five counties in Pennsylvania and has a population of 4,008,994. Popular nicknames for Philadelphia are Philly and The City of Brotherly Love, the latter of which comes from the literal meaning of the city's name in Greek (Greek: Φιλαδέλφεια ([pʰilaˈdelpʰeːa], Modern Greek: [filaˈðelfia]) "brotherly love", compounded from philos (φίλος) "loving", and adelphos (ἀδελφός) "brother").
Philadelphia was founded on October 27, 1682 by William Penn, who planned a city along the Delaware River to serve as a port and place for government. The city grew rapidly, and by the 1750s Philadelphia was the largest city and busiest port in the original 13 American colonies. During the American Revolution, Philadelphia played an instrumental role as a meeting place for the Founding Fathers of the United States, who signed the nation's Declaration of Independence on July 4, 1776 and the Constitution on September 17, 1787. Philadelphia served as one of the nation's many capitals during the Revolutionary War, and the city served as the temporary national capital from 1790 to 1800 while Washington, D.C. was under construction. During the 19th century, Philadelphia became a major industrial center and a railroad hub that grew from an influx of European immigrants. The city's dominant textile industry represented 40 percent of total United States output in 1906. It became a major destination for African Americans during the Great Migration and surpassed 2 million occupants by 1950.
Philadelphia has transitioned from being a manufacturing powerhouse to an information and service-based economy. Financial activities account for the largest sector of the metro economy, and it is one of the largest health education and research centers in the United States. Philadelphia's history attracts many tourists, with the Liberty Bell receiving over 2 million visitors in 2010. The Delaware Valley contains the headquarters of thirteen Fortune 500 corporations, five of which are in Philadelphia proper.With a gross domestic product of $388 billion, Philadelphia ranks ninth among world cities and fourth in the nation.The city is also the nation's fourth-largest consumer media market, as ranked by the Nielsen Media Research.
Philadelphia is known for its arts and culture. The cheesesteak and soft pretzel are emblematic of Philadelphia cuisine, which is heavily influenced by the city's immigrant population. The city has more outdoor sculptures and murals than any other American city,and Philadelphia's Fairmount Park is the largest landscaped urban park in the world. Gentrification of Philadelphia's neighborhoods continues into the 21st century and the city has reversed its decades-long trend of population loss.
The Climate of the USA
The United States includes a wide variety of climate types due to its large size, range of geographic features, and non-contiguous arrangement. In the contiguous United States to the east of the 100th meridian, the climate ranges from humid continental in the north to humid subtropical in the south. The southern tip of Florida is tropical. The Great Plains west of the 100th meridian are semi-arid. Much of the Rocky Mountains, the Sierra Nevada, and the Cascade Range are alpine. The climate is arid in the Great Basin, desert in the Southwest, Mediterranean in coastal California, and oceanic in coastal Oregon and Washington. The state of Alaska—on the northwestern corner of the North American continent—is largely subarctic, with an oceanic climate in its southern edge and a polar climate in the north. The archipelago state of Hawaii, in the middle of the Pacific Ocean, is tropical.
Extreme weather is not uncommon—the states bordering the Gulf of Mexico are prone to hurricanes, and tornadoes regularly occur in the area of the Midwest referred to as Tornado Alley. The United States has more tornadoes than the rest of the countries of the world combined.
The main influence on weather in the United States is the polar jet stream, which brings in large low pressure systems from the northern Pacific Ocean. Once a Pacific cyclone moves over the Great Plains, uninterrupted flat land allows it to reorganize and can lead to major clashes of air masses. 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 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; winds can be extreme; and the flow of heat waves or Arctic air masses often advance uninterrupted through the plains.
The Great Basin and Columbia Plateau (the Intermontane Plateaus) are arid or semiarid regions that lie in the rain shadow of the Cascades and Sierra Nevada. Precipitation averages less than 15 inches (38 cm). The 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.
The characteristics of rainfall across the United States differ significantly across the United States and its possessions. Late summer and fall extratropical cyclones bring a majority of the precipitation which falls across western, southern, and southeast Alaska annually. During the fall, winter, and spring, Pacific storm systems bring most of Hawaii and the western United States much of their precipitation. Nor'easters moving up the East coast bring cold season precipitation to the Mid-Atlantic and New England states. Lake-effect snows add to precipitation potential downwind of the Great Lakes, as well as Great Salt Lake and the Finger Lakes during the cold season. The snow to liquid ratio across the contiguous United States is 13:1, meaning 13 inches (330 mm) of snow melts down to 1 inch (25 mm) of water.The El Niño-Southern Oscillation affects the precipitation distribution, by altering rainfall patterns across the West, Midwest, the Southeast, and throughout the tropics.
During the summer, the Southwest monsoon combined with Gulf of California and Gulf of Mexico moisture moving around the subtropical ridge in the Atlantic ocean bring the promise of afternoon and evening thunderstorms to the southern tier of the country as well as the Great Plains. Equatorward of the subtropical ridge, tropical cyclones enhance precipitation across southern and eastern sections of the country, as well as Puerto Rico, the United States Virgin Islands, the Northern Mariana Islands, Guam, and American Samoa. Over the top of the ridge, the jet stream brings a summer precipitation maximum to the Great Lakes. Large thunderstorm areas known as mesoscale convective complexes move through the Plains, Midwest, and Great Lakes during the warm season, contributing up to 10% of the annual precipitation to the region.
In northern Alaska, tundra and arctic conditions predominate, and the temperature has fallen as low as −80 °F (−62 °C). On the other end of the spectrum, Death Valley, California once reached 134 °F (56.7 °C), the second-highest temperature ever recorded on Earth.
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 inches (1,758 cm); the record there was 1,122 inches (2,850 cm) in the winter of 1971–72. This record was broken by the Mt. Baker Ski Area in northwestern Washington which reported 1,140 inches (2,896 cm) 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, near Lake Tahoe.
Along the coastal mountain ranges in the Pacific Northwest, rainfall is greater than anywhere else in the continental U.S., with Quinault Ranger Station in Washington having an average of 137 inches (3,480 mm). Hawaii receives even more, with 460 inches (11,684 mm) measured annually, on average, 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 (67 mm) of precipitation each year.
The United States is affected by a large variety of weather related natural disasters. Deadly and destructive hurricanes occur almost every year along the Atlantic seaboard and the Gulf of Mexico. Hurricanes can also strike 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. 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.
The Great Plains, the Midwest and the southern United States - because of the contrasting air masses - have frequent severe thunderstorms and tornado outbreaks during spring and summer. In central portions of the U.S., tornadoes are more common than anywhere else on Earth and touch down most commonly in the spring and summer. The strip of land from north Texas north to Nebraska and east into Southern Michigan is known as Tornado Alley, where many houses have tornado shelters and many towns have tornado sirens. Stretching across Mississippi and Alabama, Dixie Alley has experienced tornadoes and violent thunderstorms. Florida also reports many tornadoes but these are rarely very strong. The southern USA has a second tornado season during the Fall.
The Appalachian region and the Midwest experience the worst floods. 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 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. 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 floods as well, while Nor'easter snowstorms can bring activity to a halt throughout the Northeast (although heavy snowstorms can occur almost anywhere).
The Southwest has the worst droughts; one is thought to have lasted over 500 years and to have decimated the Anasazi people. Large stretches of desert shrub in the west can fuel the spread of wildfires. 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.