Geographical Features

The United States of America, also called the USA, the U.S. or simply America, is a federal republic of 50 states [E1] [E2] and one federal district, where the capital, Washington DC [E1] [E2], is located.

The United States stretches from Canada to Mexico for 2,500 Km and from the Atlantic to the Pacific Ocean for 4,600 Km. The mainland crosses four time zones from coast to coast:  Eastern, Central, Mountain and Pacific, so there is a 3-hour difference between New York and San Francisco.

Two of the fifty states which form the confederation are separated from the mainland: Alaska lies north-west of Canada, the Hawaii Islands are in the North Pacific Ocean, 3,000 Km off the west coast.

 Landscape

The landscape of the United States is quite various: the diversity of the country derives from the fact that it is so large and has so many kinds of climate: from coast to coast one can find high mountain chains, fertile valleys and desert plains as well.

As regards mountain chains, there are three systems that run vertically through mainland U.S. : the Appalachians from Maine to Alabama are the oldest and are quite low, the Rocky Mountains or Rockies from Alaska to Mexico are young, rough and irregular in shape, the Sierra Nevada Mountains and the Coast Ranges, between which lies California, are as high as the Rockies. Nevertheless, the highest mountain in the U.S., Mount McKinley, is in Alaska and is 6.194 m high.

Between the Rocky Mountains and the Appalachians lie the so-called Interior Plains. This region is divided into two parts: the eastern one, called Central Lowland, is crossed by many rivers and is very fertile.; the western is called the Great Plains and is covered with tough grass and more suitable for animal farming than agriculture. The Great Plains become high plateaus crossed by gorges and canyons in Colorado and New Mexico. The most popular is the Grand Canyon of the Colorado river. The regions of Nevada, Arizona, Utah and New Mexico are largely desert and hot.

The most largest lakes [E1] [ES1] in the United States are the Great Lakes [E1] [F1], which represent the world’s largest group of fresh-water lakes. They include: Lake Ontario, Erie, Huron, Michigan and Superior. Between lake Erie and Ontario there are the famous Niagara Falls. Another large lake is the Great Salt Lake in Utah, which derives its name from its salty waters.

The main rivers [E1] [E2] [E3] [ES1] in the U.S. are the Mississippi, which is also one of the world’s greatest ones, the Missouri, the Ohio, the Columbia, the Colorado and the Rio Grande. These are just the main ones, but the States are very rich of rivers (37 total) and they represent an enormous resource of power and irrigation, together with a transportation route. The Mississippi has been a major transportation route throughout the history of the U.S. and today it still is a quite busy navigable waterway.

Climatic Conditions

The weather in the U.S. varies a lot all around the country, ranging from the subarctic climate of Alaska to the subtropical climate of Hawaii and southern Florida.

The middle and northern Atlantic states, the Midwestern states and the Great Plains states have a continental climate, with hot summers and cold (sometimes extremely cold) winters.

Some Rocky Mountains areas have an alpine climate, while Nevada, Arizona and most New Mexico have warm winters, very hot summers and little rainfall.

The climate of the Pacific coast states depends on the mountains, distance from the ocean and altitude: it is generally dry and warm in the south, wetter and colder in Oregon and Washington.

In the south central states summers are warm and humid and winters are quite temperate thanks to the influence of the warm stream of air coming from the Gulf. But in spring and summer many destructive hurricanes are very frequent and of varying degrees of intensity: probably one of the deadliest natural disasters in the U.S. history was Hurricane Katrina [E1] [E2] [ES1] [I1], which battered New Orleans on 29^th August 2005.