here I some comments (I got on facebook when i asked about this:
This year we turned ours in but for the past 3 years we have not and we had no issues crossing. We were told by one agent a couple of years ago that it is not necessary because when they expire they are no longer in the system.
Haven't turned one in yet after 5 trips thru Nogales over 5 years.
This year we turned ours in but for the previous 3 years we did not. It was never a problem coming back. In fact one agent told us that it was not necessary that once they expire they are no longer in the system.
