"Hi"...when you come to Canada either by sea air or land from the U.S. you "AUTOMATICALLY" visit , stop or are channelled to Canadian Customs ( and Immigration ) and have nothing to do with U.S. Customs.
Subsequently when you leave Canada for the return back home to the U.S. then you only check in with U.S. Customs.
One doesn't have to check with Customs when leaving a country but only the appropriate Customs when entering a country !
Glad to help and a "Welcome" to Canada ! *S* (Michael C...)

