Mass Legal immigration and illegal immigration go hand in hand. When we had a much smaller legal hispanic population we had a much smaller illegal immigration problem. Ethnic enclaves of legal immigrants provide the sanctuary and refuge for illegals. The legal immigrants often provide the cover and immediate sustenance for their illegal relatives.
The correlation between high levels of legal immigration and illegal immigration is but one reason why the new amnesty bill will dramatically ratchet up future illegal immigration. Why? Because it dramatically ratchets up legal immigration.