Like Ajidica said, I think the Spanish tended to mix more as most of them didn't bring women with them since they came as soldiers and conquerors. Still needing to have sex, they took native wives or (probably more often) raped their slaves. Also, the areas the Spanish colonized were much more densely populated with Native Americans in the first place.
Canada actually has a fair population of mixed French and Natives. See the Metis: http://en.wikipedia.org/wiki/Métis_people_(Canada)
Canada actually has a fair population of mixed French and Natives. See the Metis: http://en.wikipedia.org/wiki/Métis_people_(Canada)