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From NPR News, this is ALL THINGS CONSIDERED. I'm Audie Cornish.
MELISSA BLOCK, HOST:
And I'm Melissa Block.
President Obama was in Las Vegas today, making the case for one of his key campaign issues.
PRESIDENT BARACK OBAMA: The time has come for common sense, comprehensive immigration reform.
OBAMA: The time has come.
BLOCK: We're covering specifics of the president's plan elsewhere in the program. Some elements dovetail with the plan announced yesterday by a bipartisan group of senators. For the next few minutes, we're going to talk about current border security. One key claim the president made is that his administration has already strengthened the border.
OBAMA: We put more boots on the ground on the southern border than at any time in history. And today, illegal crossings are down nearly 80 percent from their peak in 2000.
CORNISH: NPR's Ted Robbins joins us now. And, Ted, to start, the Senate plan demands that borders be more secure before any citizenship process is actually put in place. And, of course, the White House says that border is already much more secure than it used to be. How do we know?
TED ROBBINS, BYLINE: Well, we don't. But it's hard to believe that with all the money spent and the tens of thousands of Border Patrol agents and aircraft that it is less secure. And some numbers support that contention that it's more secure. The question is, what is secure enough and how do we know when we get there? And the big problem has been that the Department of Homeland Security does not have a measurement to say how effective it's been or what is secure.
It's been working on a measurement called the Border Security Index for three years, still not ready. And some people in Congress wanted to go back to an old thing called Operational Control - how many miles do agents hold.
CORNISH: So help us understand in numbers that we do know.
ROBBINS: Yeah, the numbers definitely show something. The recent high point was in 2005, 1.1 million people were apprehended crossing illegally. Well, the last numbers were for fiscal year 2011. That number went for 1.1 million to 340,000. So we're down two-thirds and the lowest levels in 40 years.
CORNISH: And, of course, research has shown that illegal immigration into the U.S. has slowed in recent years for a number of reasons. Talk about those reasons and how that affects border enforcement.
ROBBINS: Well, the primary reason the numbers have gone down, everybody agrees, is that the U.S. economy tanked in 2008; lack of jobs, lack of a magnet to bring people here. The other reason is that there are 11 million people already here illegally, and they used to migrate - go back and forth. Now, with all the enforcement, it's harder to come and go and so many have stayed here in the U.S.
And lastly, the Mexican economy is improving. It's growing at a faster rate than the U.S. economy and so there may be less of a need for people to leave.
CORNISH: One thing, Ted, is back in 2006, the Secure Fence Act implemented a plan to fortify the southern border of the U.S. What's the status of that fence? Do people think it worked?
ROBBINS: Well, the fence, it seems to be working very well keeping illegal traffic out in urban areas, like San Diego and Nogales, El Paso. Not as well if you go a few miles outside of the urban areas. It has to be regarded in some ways with bodies, cameras, aircraft, and maintained pretty much 24/7 as crossers breach it.
Remember, the border is 2,000 miles long. There are 700 miles of fencing and nobody thinks that there's going to be fencing over mountain ranges, rivers and cities and Indian nations.
So the other fence, quote, in quotes, is a series of towers, you know, with cameras, radar sensors, and there's been some mixed success with that, and the thousands of ground sensors along the border.
CORNISH: And lastly, Ted, we've been talking about border security but what about the ports of entry - noncitizens who enter legally?
ROBBINS: Right, and the estimates there are from a third to a half of all the people in the United States illegally now came in legally and overstayed their visas. No amount of border security is going to solve that problem.
CORNISH: NPR's Ted Robbins, Ted, thank you.
ROBBINS: You're welcome. Transcript provided by NPR, Copyright NPR.