Question

Why are cattle ranchers generally found in northern Mexico?

Answer 1

I think the question is asking why they're not find in southern Mexico. Southern Mexico does not have the proper climate, as it's mostly filled by Jungles (Chiapas, Yucatan, etc) - and cattle would have problems going through the jungle. Cattle needs plains with grass, and this is rather found in the north of Mexico, which is not as humid as the south