The Trump administration seems to be aiming for a rough relationship with our southern neighbor, and rules and regulations may change at any moment. Keep up with any changes in immigration law via these excellent online resources:
Mexperience is an all-encompassing website for anyone interested in relocating to Mexico. Tons of info on culture, costs, health care, and realestate. They offer a $20 ebook which is a wise investment for anyone even thinking about a move. Their free newsletter is an education in and of itself.
Transitions Abroad is another must. Lots of current information on all aspects of Mexico for workers and retirees alike.
Mexonline is a solid choice for information as well for potential migrants. Job offers, a classified section, and lots of background info on where to live. Great recipes too!
The Mexican government is not known for its user-friendliness, and the Government of Mexico website for potential migrants is no different. You're much better off actually visiting your local consulate if at all possible (there are dozens scattered throughout the USA).