When you leave the U.S, you should give the Form I-94 to your airline representative. If you arrive in Canada by land then you may give your I-94 to a Canadian Immigration inspector. However, you may have difficulty finding one willing to accept it. In this case, you are advised to follow the instructions below.
What If No One Takes Your I-94 Form Upon Departure
Failure to turn in your I-94 (or I-94W) when you leave the U.S. can create a serious problem. Without this record of your departure, you will be identified in our records as an "overstay." Being identified as an overstay means that you will be denied re-entry into the U.S. If you failed to turn in your I-94, please send it - along with any documentation that proves you left the U.S. to ACS Inc. 1084 South Laurel Rd., London, Kentucky 40744.
Documentation to prove your departure can include the boarding pass from your flight. If you exited the country by a land border it is much harder to verify that you did- in fact - leave the country on the date you claim. If you have any documentation of your arrival in your home country (i.e. passport stamp), then you should send a copy of that. If the above office does not have any supporting documents to substantiate your claim to have left the U.S. on a certain date, there is no guarantee that you will be entered into the record as having done so. We strongly urge you to keep a copy of what you send to ACS Inc. and to carry it with you the next time you come to the U.S. in case the CBP officer has any questions about your eligibility to enter.
If you want to confirm that your I-94 was received by ACS, please give them 4 months to process the paperwork. Then you can write the following address to determine whether or not your departure was recorded. If you turned in the I-94 when you left the U.S. as required, please do NOT request confirmation that it is on file. This process is only for people who did not turn in the I-94 when they exited the U.S.
You will need to provide your name, date of birth, passport number, and date of departure, in addition to asking whether or not your departure was recorded. U.S. Customs and Border Protection Air Sea Passenger Operations, Room 5.4D, 1300 Pennsylvania Ave., N.W., Washington D.C. 20229.
http://www.cbp.gov/xp/cgov/travel/id_vi ... ut_i94.xml
