The USA: geography

THE USA

1.      LOCATION

The USA stretches from Canada to Mexico and from the Atlantic to the Pacific Ocean covering an area of about nine and half million square kilometres.

Two of the States are separated from the mainland:

–      ALASKA lies north-west of Canada

–      HAWAII ISLANDS lie in the north Pacific Ocean, 3000 km off the west coast.

The USA also includes island territories:

–      in the Carribean PUERTO RICO

                                 VIRGIN ISLANDS

–      in the Pacific MIDWAY ISLANDS

                             AMERICAN SAMOA

                             GUAM

–      in the Bering Sea ALEUTIAN ISLANDS

Being 4600 km coast to coast, the mainland US crosses four times zones:

EASTERN time

CENTRAL time

MOUNTAIN time

PACIFIC time

so there is a 3-hour difference between New York and San Francisco.

2.      THE MOUNTAINS

The highest mountains in the US are in Alaska: among them is MOUNT MC KINLEY, the highest point in the country 6190 m.

Three mountain systems run vertically through mainland US:

●      The westernmost mountain system includes the COAST RANGES and the CASCADE RANGE which lie along the Pafcific Ocean, the SIERRA NEVADA where MOUNT WHITNEY rises to a height of 4418 m.

Between the Coast Range and the Sierra Nevada lie the fertile valley of California.

●      The ROCKY MOUNTAINS or ROCKIES that stretch all the way down from Alaska to Mexico.

Their main range called the Continental Divide separates the rivers flowing into the Pacific from flowing eastwards.

●      The eastern mountain system is formed by the APPALACHIANS, a series of chains extending from Maine down to Alabama.

The highest peak in the Appalachians is MOUNT MITCHELL (in North Carolina 2037 m.).

To the east of the Appalachians lies a coastal plan that in the northern states is covered by thick forests.

INTERIOR PLAINS

Between the Rockies and the Appalachians lies a vast lowland: the Interior Plains, divided into two distinct parts:

• CENTRAL LOWLAND: the eastern part -  it is crossed by many rivers and the soil is very fertile 
• THE GREAT PLAINS: the western part - here the soil is covered by tough grass so that agricolture is limited to the few sections where irrigation has been provided.             

CANYONS

In Colorado and New Mexico the Great Plains gradually rise in height becoming plateaus crossed by gorges and canyons such as the famous GRAND CANYON of the Colorado river.

DESERTS

The intermontane regions in  UTAH, NEVADA, ARIZONA and NEW MEXICO are largely desert.

The most famous desert in the US is in California: DEATH VALLEY  is nearly 100m below the sea level and one of the hottest areas on earth.

3.    THE RIVERS

The rivers of the US are of enormous importance to the country.

The main rivers flowing into the PACIFIC OCEAN are the          

• SACRAMENTO
• COLUMBIA
• COLORADO

 The main rivers flowing into the ATLANTIC OCEAN are the      

• HUDSON (New York 's river)
• SUSQUEHANA
• POTOMAC (Washington's river)
• SAVANNAH

The main rivers flowing into the GULF OF MEXICO are the       

• RIO GRANDE
• MISSISSIPPI

The MISSISSIPI is the most important in terms of size and length (about 6000 km). It receives almost 250 tributaires, the chief of which is the MISSOURI; then the ARKANSAS and the RED RIVER, all flowing from the Rockies; the ILLINOIS, the OHIO and the TENNESSEE, all flowing from the Appalachians.

The main cities standing on its banks are Minneapolis, St. Louis and New Orleans.

The RIO GRANDE is about 3000 km. long and it forms a natural boundary between the US and Mexico.

The ARKANSAS is about 2320 km. long.

The COLORADO is one of the longest rivers in the country (2320 km.) and with its tributaries supplies water and hydroelectric power to seven states.

Other rivers:

The OHIO 2089 km

The RED RIVER 1955 km.

The COLUMBIA 1942 km.

The SNAKE 1660 km.

The TENNESSEE 1390 km.

5.   THE LAKES

In the North-West there are five immense likes:

• LAKE HURON
• LAKE SUPERIOR
• LAKE MICHIGAN
• LAKE ERIE
• LAKE ONTARIO

Between Lake Erie and Ontario there are the famous NIAGARA FALLS which provide about 4 million kilowatts of electricity to Canada and US.

These five likes are estimated to contain about half of the word's fresh water; tourist from all North America are attracted by the beauty of this area, which is also rich in minerals.

The St Lawrence River connects the lakes with the Atlantic and allows access to the industrial cities throught a system of navigable canals.

In the state of UTAH there is the GREAT SALT LAKE; it is also very large and its water contains a very high percentage of salt.

6.    CLIMATE

The US is a vast country with a great variety of climatic conditions:

• SUBARCTIC CLIMATE of Alaska
• SUBTROPICAL CLIMATE  of Hawaii, south Florida, to the desert areas in Nevada and California
• CONTINENTAL CLIMATE  with hot summers and cold winters but the amount of precipitations is different:

                                                           of the Middle and Northern Atlantic States

                                                           of the Midwestern states

                                                           of the Great Plains states

• ALPINE CLIMATE  in the Rocky Mountains

●              Along the coast on the Gulf of Mexico summers are warm and humid, winters are quite

            temperate thanks to the influence of the warm stream of air coming from the Gulf

●              All the south central states in spring are battered by recurring destructive hurricanes.

●              Of the Pacific coast states the climate depends on the mountains, distance from the

            ocean and latitude. It is generally dry and relatively warm in the south, wetter and colder
            in  Oregon and Washington.

By Nicola Basso, 2LSA