The United States of America take fourth place in top of 'The biggest countries in the world'. In the east and in the west the USA wash Pacific and Atlantic oceans. In the north and in the south USA borders Canada and Mexico...
The the highest mountain chains of the USA is Rocky Mountains, but these are not the oldest one. The oldest are The Appalachian Mountains. 
The hottest, driest and the lowest place of North America is Death Valley. It is unusual place, too. 
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