North America, the third-largest continent, extends from the tiny Aleutian Islands in the northwest to the Isthmus of Panama in the south. The continent includes the enormous island of Greenland in the northeast and the small island countries and territories that dot the Caribbean Sea and western North Atlantic Ocean. In the far north, the continent stretches halfway around the world, from Greenland to the Aleutians. But at Panama's narrowest part, the continent is just 50 kilometers (31 miles) across. North America's physical geography, environment and resources, and human geography can be considered separately.
North America can be divided into five physical regions: the mountainous west, the Great Plains, the Canadian Shield, the varied eastern region, and the Caribbean. Mexico and Central America’s western coast are connected to the mountainous west, while its lowlands and coastal plains extend into the eastern region. Within these regions are all the major types of biomes in the world. A biome is a community of animals and plants spreading over an extensive area with a relatively uniform climate. Some diverse biomes represented in North America include desert, grassland, tundra, and coral reefs.
Young Mountains rise in the west. The most familiar of these mountains are probably the Rockies, North America's largest chain. The Rockies stretch from the province of British Columbia, Canada, to the U.S. state of New Mexico. The Rocky Mountains are part of a system of parallel mountain ranges known as the Cordilleras. A cordillera is a long series of mountain ranges. Although cordilleras exist all over the world, in North America, “the Cordilleras” indicate the massive mountain ranges in the western part of the continent. The Cordilleras extend from Canada all the way to the Isthmus of Panama. The Sierra Madre mountain system is part of the Cordilleras. The Sierra Madre stretch from the southwestern United States to Honduras. The Sierra Madre include many high volcanoes (up to 5,636 meters, or 18,500 feet) that stretch across Mexico south of the cities of Guadalajara and Mexico City. Volcanic mountain ranges in Guatemala, Honduras, Nicaragua, Costa Rica, and Panama are also considered part of the Cordilleras. Volcanic eruptions and earthquakes occur frequently in this region. Volcanic activity can destroy towns and cities. It also contributes to the rich, fertile soils of the region. Some of the Earth’s youngest mountains are in the Cascade Range of the U.S. states of Washington, Oregon, and California. Some peaks began to form only about a million years ago-a blink of an eye in Earth’s long history.
The mountains include temperate rain forest-a biome unique to the area. The temperate rain forest receives an incredible amount of precipitation, between 254 to 508 centimeters (100 to 200 inches) annually. However, its cool winters and mild summers promote the growth of mosses, ferns, fungi, and lichens. The temperate rain forest supports a wide variety of life. The Sitka spruce, western red cedar, and Douglas fir are trees native to North America’s temperate rain forest. Some of these trees grow to more than 90 meters (300 feet) tall and 3 meters (10 feet) in diameter. Black bears, Roosevelt elk, and marmots are indigenous animal species. The three major desert regions of North America-the Sonoran, Mojave, and Chihuahuan-are all in the American southwest and northern Mexico.
These large deserts are located in the rain shadows of nearby mountains. The mountains block precipitation and accelerate the movement of hot, dry wind over these regions. The Sonoran is in the rain shadow of the Coast Ranges, the Mojave is in the shadow of the Sierra Nevada, and the Chihuahuan is in the shadow of the Sierra Madre. Notable desert plant species includes the saguaro cactus, Joshua tree, and mesquite. Animal species include the roadrunner, Gila monster, and rattlesnake. In addition to mountains, deserts, and forests, the northern part of the western region of North America also has the richest deposits of oil and natural gas on the continent. Most of these deposits are located offshore, in the Arctic and Pacific Oceans.
The Great Plains lie in the middle of the continent. Deep, rich soil blankets large areas of the plains in Canada and the United States. Grain grown in this region, called the “Breadbasket of North America,” feeds a large part of the world. The Great Plains are also home to rich deposits of oil and natural gas. Much of the fertile soil was formed from material deposited during the most recent glacial period. This ice age reached its peak about 18,000 years ago. As glaciers retreated, streams of melted ice dropped sediment on the land, building layers of productive soil. The grassland or prairie regions of the Great Plains make up the largest biome in North America. Extreme weather prevents the growth of large plants but is perfectly suited to the native grasses that dominate the region. Native grasses vary in size from 2 meters (7 feet) in tallgrass prairies to only 20 or 25 centimeters (8 or 10 inches) in shortgrass prairies. Native animal species include bison, prairie dogs, and grasshoppers.
This varied region includes the Appalachian Mountains and the Atlantic coastal plain. North America’s older mountain ranges, including the Appalachians, rise near the east coast of the United States and Canada. These areas have been mined for rich deposits of coal and other minerals for hundreds of years. The Atlantic coastal plain extends from river, marsh, and wetland regions east of the mountains toward the sandy beaches of the Atlantic coast. Wetland areas are a biome of the eastern region and consist of areas of land whose soil is saturated with permanent or seasonal moisture. The Florida Everglades is the largest wetland system in the United States, covering more than 11,137 square kilometers (4,300 square miles) of southern Florida. The Everglades is a biologically diverse region and contains several bordering ecosystems. Sawgrass marshes are the most iconic plant community of the Everglades and thrive on the slow-moving water of the wetlands. Alligators nest in the sawgrass, while wading birds such as egrets, herons, spoonbills, and ibises make their breeding grounds in other wetland tree species, such as cypress and mangrove.
North America’s varied landscape features many natural wonders. It has deep canyons, such as Copper Canyon in the Mexican state of Chihuahua. Denali, the continent’s highest peak, stands at 6,194 meters (20,320 feet) within Denali National Park and Preserve in the U.S. state of Alaska. Yellowstone National Park, in the U.S. states of Wyoming, Montana, and Idaho, has some of the world’s most active geysers. Canada's Bay of Fundy has the greatest tidal range in the world. The Great Lakes form the planet's largest area of freshwater. The Mississippi River, at 3,730 kilometers (2,320 miles) long, is one of the longest river systems in the world and drains all or parts of 31 U.S. states.