I have recently been given a green card by mail and traveled overseas last week. However, my I-94 was not collected at the airport when departing since I had my green card. When returning, the immigration officer noticed that my I-94 was still in my passport and instructed me to mail it out to one of their offices since it should have been collected and could be a problem in the future. My question is, once the green card is approved, does my I-94 become suspended and if so, is it a standard procedure to have them mailed out to USCIS? I am curious to know since my wife was also granted permanent status and would like to know if we should also mail out her I-94 to USCIS, or if it should be surrendered at the airport upon departure. Any information would be appreciated. Thanks.