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The United States is often called ``America,'' but this name really
belongs to the two huge continents of the Western Hemisphere--North
America and South America. Part of North America, the seven countries
from Guatemala to Panama, is called Central America.
The two continents stretch 9,500 miles (15,288 km) from north to south.
Together the continents cover about 28 percent of the Earth's land
surface. They vary in width from just 30 miles (48 km) in Panama to
more than 4,000 miles (6,440 km) across Alaska and Canada.
Many scientists believe that millions of years ago the land masses
of America were joined to the western edge of Europe. Some rock forms
of the ...