Well, another accountability for the reduction of undocumented immigrants is due to our economic downfall. If Americans are having a hard time finding a job, imagine how hard it is for someone who isn't authorized to work!
Not only that, but it has become very difficult to live a "normal" life for immigrants after 9/11 occurred. It is as if every foot-step has a stamp saying let me see your ID, or most importantly what is your SS#? It has been extremely hard since most things that used to be accessible isn't anymore. (I think people here know what I mean).