The USA is the 4th largest country in the world (after Russia, Canada and China). Including the states of Alaska and Hawaii, the US covers an area of 9 millions square km. It borders Canada on the North. Besides, it is such a big country that it covers 4 time zones. Almost every kind of climate may be found there but the country lies mostly in the temperate zone. The US is a varied land of forests and mountains. If we look at the map of the USA, we can see lowlands and mountains. The center of the country is drained by the Mississippi and Missouri rivers. These rivers form a 19000 km system of water ways that are connected to the Great Lakes in the North by a canal. The Mississippi is one of the world's great rivers; it was known to American Indians as the "father of waters". To the north – on clear days, passengers may see the five Great Lakes located between the US and Canada. The USA is one of the greatest industrial nations in the world. With only about 5% of the world's population and about 6% of its land area, The US produces around 25% of the world's industrial products, agricultural goods, and services. There are many reasons, which can be explain why the USA has been able to become the leading industrial and agricultural nation. One is its size and natural resources. The rapid progress of American industry and agriculture is also the result of the constant willingness to experiment and to find new solutions to old problems. The USA has often been called "a nation of immigrants" because the country was built and developed by generations of immigrants. Even today America continues to take in more immigrants than any other country in the world. But in spite of all the different cultural traditions, nation origins, racial groups, and religions, this vast land is one country, whose people speak the same language, are part of the same culture and follow the same national laws and regulations. The American people are always on the move – from one part of the country to another, from farm to city, from the city to the suburbs. 17% of all Americans move to new homes every year, searching for job opportunities, a better climate, or for other reasons. Today 3 out of 4 Americans live in towns, cities or suburbs. The largest cities of the USA are New York, Los Angeles, Chicago, Boston, Philadelphia, Detroit, Houston, Baltimore, San Francisco. New York city is America's largest city. Its population in1990 was 7.3 million. It is a city of great beauty and it is also a leading cultural center. The USA is a federal republic, a union of 50 states. The flag of the USA is called "Stars and Stripes". In the USA the American flag is a very important Symbol of the country and is supposed to be treated with respect.