The drop was mainly due to the souring economy not the lackluster border work although the few workplace raids helped a little although they were far a few...
I always have believed that GWB used his available resources to track down Jihadists after 9/11, not chase Mexicans.
How about the Hezzbolla and Hamas infiltration of the southern border as reported by the FBI and Homeland Security!... Doesn't seem like the border was that secure!
We have yet to be attacked by Muslims using the southern border for access..
Besides, you can never defend our porous borders enough to keep small determined groups of men from crossing it. That's why you kill the bastards in Iraq, Afghanistan, Yemen, and Somalia.