i-551 stamp

[crowskeet]

My wife has lost her green card so we already completed the application for the replacement green card. But, the wait can sometimes be up to a year to receive the new card. Her sister is dying and we must travel to Mexico to see her.
My wife already got the i-551 stamp in her passport this week. Is she guaranteed re-entry with it? We even have photo copies of her green card, but with this new administration are these types of situations not guaranteed and she could possibly be stuck in Mexico indefinitely?

[newacct]

Yes, it's equivalent to a green card (which is also just an I-551 document). She will definitely have no problem entering the US with it; but occasionally foreign airline staff might not know what it is.