When Canadians travelling with a US entry waiver enter the United States by land they are typically issued an I-94 card which is stapled into their passport. The card is not issued to travellers who enter the country by sea or air. We don’t know why.
The I-94 is sometimes issued for the length of the traveller’s stay in the US. However, it is more commonly is issued for a period of 6 months since this is the longest amount of time a Canadian can remain in the US as a visitor.
Travellers are frequently instructed to return the card to border officials when they leave the US and they are sometimes warned that failure to do so will have negative consequences. However, in our experience Canadian border officials tend to refuse to accept the I-94 card from returning travellers. As a result, we are often contacted by concerned travellers who have been unable to return the I-94. We have never documented a case in which failure to return the I-94 has led to negative consequences for the traveller.
Moreover, travellers who have been issued an I-94 valid for six months can re-enter the US with the previously issued I-94 for the remaining six month period. Once the card is expired a new I-94 will be issued after six months. Accordingly, we advise travellers that there is no need to return the I-94 upon re-entry into Canada.
However, the purpose of the I-94 is to track entry and exit from the US and CBP specifically states that anyone who fails to return the card will be registered as an “overstay” in the US and “may be denied entry when they attempt to re-enter the United States in the future.”
Nevertheless, it seems unlikely that this would be the case for Canadians travelling under the waiver program. US and Canadian border authorities share information about when travellers cross the border, and commercial carriers (airlines and cruise ship operators) provide this information to US CBP. This allows CBP to determine the length of time any traveller remains in the US. As long as Canadians enter and exit the US using the same passport, CBP will be able to correctly track their entry and departure, regardless of whether or not an I-94 card has been issued and returned.