The numbers of immigrants into America are slowing as the country is getting more and more tougher and deporting more.
Certain areas will stop and search possible 'illegals' just on profiling, this turning people off of possibly entering the country. Although I definitely think that the recession has had a large part to play in the downturn.
It would be intresting to see what peoples opinions are on immigration into Canada and why this is going from strength to strength.
This is an interesting article on http://www.ideamarketers.com/?articleid=775090l Canada immigration compared to US.