There are some significant cultural/heritage differences between Mexico and the United States. The current population of Mexico is a result of large scale admix

There are some significant cultural/heritage differences between Mexico and the United States. The current population of Mexico is a result of large scale admixture between indigenous people and European colonists, whereas essentially no such admixture occurred in the US. Also, the US is culturally descended from Northern Europeans, whereas the European aspect of Mexican culture is descended from Southern Europe. The Northern/Southern cultural divide in Europe is pretty significant and I would guess that, in practice, the term “The West” primarily refers to Northern Europe rather than Southern (or Eastern) Europe.