Even the Berlin Wall failed by that measure, he notes. "At that point they were shooting at unauthorized crossers," he says. "Even on a heavily fortified, militarized 37-mile wall, people were crossing. To think that nobody will cross illegally over a 2,000-mile border is fanciful."
In 2010, that realization – together with rising costs and technological challenges – led the Obama administration to kill the virtual fence.
That doesn't mean the border surge was a failure, though.
Border patrol officials say a historic decline in total apprehensions nationwide – from a peak of 1.6 million in 2006 to 356,873 in 2012 – is a sign of success. As further proof that the border is under control, the agency touts its record of intercepting a massive amount of smuggled drugs, and offers FBI statistics showing that crime is lower in border areas than in some parts of the US interior.
"The high-speed chases, the rollovers, the chaos that comes with a border out of control, that is no longer the norm," said Manuel Padilla, acting chief of the border patrol's Tucson sector, at a recent meeting. "That is no longer there."
The soft US economy has been a significant contributor to the drop in illegal entries – fewer jobs attract fewer immigrants. But other experts agree that the security surge has played a role in bringing apprehensions down to levels last seen in the early 1970s.