If you have an expired non-immigrant visa stamp in your passport (for example F or J) and you have a valid I-94 card stating your current status, your visa will be considered automatically revalidated when you re-enter the U.S. from Canada as ALL of the following are true:
- you have only been in Canada for less than 30 days
- you have with you a current I-94 card stating your valid status
- you do have an expired non-immigrant visa in your passport
- you do not apply for a U.S. visa while in Canada
- you are not from one of the countries currently considered by the U.S. federal government to be state sponsors of terrorism (as of 08/07/2003 this includes Iran, Iraq, Syria, Libya, Sudan, North Korea and Cuba)
For automatic revalidation to apply to you, you must be careful to keep your I-94 card when leaving the U.S. When you re-enter the U.S., present your I-94 card along with your valid passport, expired visa and your valid immigration document (I-20, DS-2019 or I-797 in the case of someone in H1B or O visa status).