The Andes mountain range is 7,000 km long.
The Andes Mountains line the western edge of South America, from Venezuela all the way along Chile to South America's southern tip (about 9,000 km in all), making them the longest mountain range in the world. Along that route, they cross through Ecuador, Peru, and Bolivia. By width, they cross into Argentina, which borders with Chile. The Andes are one of the tallest mountain ranges, too, trailing only the Himalayas of Asia in height. Many summits (tops of the mountains) reach higher than 20,000 feet.
Climates
Because the Andes stretch from the north end of the continent to the southern tip, the range of climates of the mountains varies. Some climates are bone-freezing cold, while others are quite warm. This has to do with the elevation of each climate, as does how close that climate is to the equator. Also, the height of each mountain can play a role in its climate. Each climate supports its own type of animal and plant life.
Regions
The Andes contain three main regions - northern, central, and southern. The northern region is closer to the equator, so it is warmer than the others. In the central region, the weather is mild, while the southern region is colder, since its mountains are further away from the equator. They are closer to the Antarctic than the other two regions.
Each country through which the Andes runs has its own peaks and regions. Traveling from the north, you can enter the Andes through the Trujillo, also known as 'The Portable City,' a small town in Venezuela. In Colombia, the Andes are divided up into two chains: the Cordillera Occidental and the Cordillera Central (the Western mountain range and the Central mountain range). Ecuador also has two chains: parallel ranges of mountains aligned from north to south. Between the two is a valley known as the Avenue of the Volcanoes.
The fact that the Andes run the entire length of Chile - a country that is 18 times longer than it is wide at its widest point makes the country virtually impassable. It's very difficult to pass from Chile into Argentina or vice versa. Also, the two chains of mountains don't end at Chile; all along the country, there is a deep, if narrow, depression.
In Chile, the Andes contain more than 50 active volcanoes. The land is notoriously treacherous; the farther south one travels, the colder it gets, yet there's also the Atacama Desert - a dangerous and inhospitable place. Chile's center is much more hospitable to life; a long river valley with farms and vineyards runs through it.
Two chains also run through Bolivia, but the names change to Cordillera Oriental (the Eastern mountain range) and the Cordillera Occidental (the Western mountain range). In the Eastern mountain range, there are peaks reaching 6,500 meters. The Western mountain range is known for its volcanic activity. It also contains desert areas. In between the two ranges is the Altiplano.