Do Mexican citizens have an identification number ? (equivatent to SSN)?

Question

My niece was born in Mexico but it has been years since she moved here. We believe she still has her Mexican nationality. She has a Mexican passport. But now that she wants to go and live there for a while, i was wondering if there's anything to prove that she is a Mexican citizen. like an identification number

Answer 1

Yes, if she has 18 years old, she can tram it her elector credential, with her certificated of borned in Mexico, address residence document in Mexico and go to the Instituto Federal Electoral in any country in Mexico.

Answer 2

The passport is the proof she is Mexican, her birth certificate is another legal proof, if she is already 18 she must get her IFE id that is the voting card, that is the official ID apart from the Passports for Mexicans.

We have Social Security number as well but is not like the US those documents above mentioned are the official and recognized Mexican IDs

Answer 3

Her passport number should be her ID number in Mexico. You might want to check her legal status at a Mexican Embassy so she doesn´t have trouble when going back to the States.  I think she will always have a Mexican nationality unless she explicity resigns to it in order to get a new one, like an American citizenship. But she can also have both. Also, make sure the passport isn´t expired, if it is, she can get a new one at the Embassy.