What is the north-south split in terms of development

The North-South split (or Rich-poor split/divide) refers to the fact that most industrialized countries are in the Northern hemisphere (think Europe and Canada/USA), while the Southern hemisphere is almost exclusively countries in development (some minor exceptions with Australia and NZ or course).

That is mostly due to the colonies established by the European countries a few centuries ago all over the world.

what events in mexico's history might explain why the country continues to have difficulty improving social justice and economic opportunities for all people?