Much has to do exactly with the flooding of people over the Southern border that isn't happening on the Northern one. There are illegals from Canada, but not very many. There's not all that many Canadians living in the US ---I know only one and even when I lived in Michigan, I only saw tourists who went back ---I never worked with a Canadian immigrant the entire time I was there.
The problem is ... the numbers of mexicans that have come here and overtaxed our systems, i.e. schools, welfare, charity organizations, hospitals, emergency rooms used as doctors for all their ailments.
Go to your emergency room a few times and look around. There is upwards of 80% of the people seeking treatment ---who are mexican
This occurrence is located disproportionally in a few states ... California, Texas, Arizona, New Mexico, Georgia, Florida,Oregon, etc. Over taxing systems faster than it has been possible to keep up with expanding them . Budgets are set ahead for these programs.
In the town where I live over 50% of the children in elementary classes are mexican. Mostly their parents are at an income level that they do not pay school tax or city tax or county tax. This is a destructive process to the systems they overburden and it is increasing.
This is a diservice to all the children as it holds back and lowers the standards for the students that do speak english and are capable of doing their grade level of education now. And on and on ... A very real problem.
Canadians do not come in these numbers, have higher level of education and speak english, to name a couple of comparisons. Often they (canadians)(as does the rest of the world) come to take advantage of the better medical care in the U. S. They pay for these services and are free to avail themselves of the higher quality of medical treatments when needed.
America's poor has more difficulty getting welfare and medical services than immigrants do. Sign of the times... Who knows?
The resulting problems are real. And so it goes ...