There are about 100,000 illegal Canadians living in the US. The US has a population of 330,000,000. I would guess that most of the 100,000 illegals from the north are white given Canada is 72% white (almost identical to the US) and most Canadians speak passable English. Additionally about 70% of Canadians live within 50 miles of the US border and have easy access to American cultural influences (sorry Canadians). So if you are white, speak English, and know that Miley Cyrus and Liam Hemsworth just split up after 7 months of marriage (I was really rooting for those two), that illegal would blend in with Americans far easier than say a non-English speaking brown guy from El Salvador. Also, if hundreds - if not thousands - of Canadians were crossing the border illegally daily, there would be detention centers filled with detained Canadians waiting to be sent back.
I saw a young lady not to long ago and someone said she was Canadian (immigration status unknown). She looked to be in pretty bad shape and kept saying, "Where's the timmies? I need timmies! PLEASE GOD! SEND ME SOME TIMMIES!" I have no idea what "timmies" means, some sort of narcotic perhaps. It was a sad thing to see.