Please make sure that upon exiting the country a border official or your travel company removes the departure portion of your I-94 (W) from your passport! This is crucial, because it is the only way for the USCIS (U.S. Citizenship and Immigration Services) to check and document whether a person has actually left the country. After you leave the country, the departure portion of your I-94 (W) will be “put together” with the original document again. If this does not happen, the USCIS can and will suspect that you are still in the country – unauthorized. This way, you can run into unexpected trouble the next time you try to enter the country and have already been blacklisted.
If you have left the country already and find that the form has not been removed from your passport, check your local US embassy website for further steps to be taken.