[Morgeruat]

link

Some Key snippets

Last year, according to the Department of Homeland Security, agents working at permanent checkpoints in the other 19 sectors detained more than 51,000 illegal aliens -- about 140 a day -- and seized nearly 450,000 pounds of marijuana and cocaine, valued at more than $700 million.

Mr. Aguilar testified before a Senate Homeland Security subcommittee that agents "cannot control our borders by merely enforcing the line," adding that the Border Patrol strategy "incorporates a defense-in-depth component" to include permanent checkpoints away from the border. "Checkpoints are critical to our patrol efforts," he said. "Permanent checkpoints allow the Border Patrol to establish an important second layer of defense." Border Patrol field agents in Arizona said the state's terrain, coupled with a limited number of highways, creates "choke points" ideal for permanent checkpoints, and that illegals who attempt to go around are targeted by mobile Border Patrol units routinely assigned as a part of a checkpoint operation.

There's more, I recommend the whole article. I can see Aguilar's point about permanent checkpoints providing a "where to go around" list for illegals, but as the field agent said, the terrain in Arizona makes suitable border crossing locations much harder to come by.