I think you are confusing this with automatic revalidation of US

來源: 於 2005-12-02 16:00:12 [舊帖] [給我悄悄話] 本文已被閱讀：次

the 30 day rule applies to visitors(US F/H/J visa holders) to canada who wish to return to US.

US green card holders do not require a visa to enter Canada, and it has nothing to do with how long you are staying there.