Comment by triceratops

> South American countries don't go to war with each other

No? Here are some examples I found:

https://en.wikipedia.org/wiki/War_of_the_Pacific

https://en.wikipedia.org/wiki/Peruvian%E2%80%93Bolivian_War_...

https://en.wikipedia.org/wiki/Peruvian%E2%80%93Bolivian_War_...

https://en.wikipedia.org/wiki/Paraguayan_War

https://en.wikipedia.org/wiki/Uruguayan_War

You may argue these were all in the 19th century, and that is true. It's possible South America learned their lesson from the world wars. An alternative explanation is the presence of the US. It was never going to let another regional power roll up smaller states in the Western hemisphere so there was no point in being expansionist.