Answer:
Its kinda celebrated in some parts of mexico, but its not an official holiday neither.
Explanation:
Before farming, people hunted animals and gathered plants (such as berries) for food: they're called hunter-gatherers.
They lived in whatever provided shelter: caves were a good candidate, but also huts made from whatver was available (mud, bamboo, wood, etc.).
The US borders Mexico, so if Mexico became a part of the axis powers the US would have to fear an attack on its mainland (from either Mexican forces or other axis forces stationed in Mexico), whereas if Mexico remained neutral the US mainland would be safe.