On the ground, though, things have turned out differently.
The DHS scaled back its ambitions early on, trimming its end-of-2008 target down to 300 miles of vehicle barrier and 370 miles of pedestrian barrier.
Just $200 million will have been spent by June, according to Lloyd Easterling, the border patrol public information officer.
Only a fraction of the new barriers resemble anything like the images of formidable fencing – the Berlin Wall or the bleak monolith that divides Israel and the West Bank – envisioned by the initial proposal. Most of the new fencing is not a double wall, but a combination of regular vehicle blocks and pedestrian barriers that range from metal mesh and chain link to traditional picket fences.
And partly because of resistance from local landowners, the December deadline would be tough to meet, US government auditors have warned.
Yuma's formidable fence
In Yuma, at least, the fence seems to be preventing illegal border-crossings.
Bernacke, the patrol agent, says that since the triple fence was finished in October, there has been a 72 percent decline in illegal migrant apprehensions in the 120-mile swath of the US-Mexican border known as the Yuma sector. Eight hundred people used to be apprehended trying to cross the border here every day. Now, agents catch 50 people or fewer daily.