True, streamlined immigration is the best way to operate. Minimize the amount of work/ time required for people to legally move to the United States. Create something of a realistic system, like what we've seen at various times in the nations history (1870's or 1910's). Make it so easy to legally immigrate that people wouldn't dream of illegally immigrating, and gain some actual control over the situation.
Also, this would save untold billions of dollars.