TUCSON, Ariz. (AP) - Border Patrol apprehensions are continuing to drop along the Mexican border, a sign that changes in policy and increased resources are paying off, U.S. Border Patrol officials say.

What's missing at this point is comprehensive immigration reform that would remove the economic pressure driving most illegal immigrants to come to the United States, said Xavier Rios, a Border Patrol national headquarters spokesman.

"If there's a way that the pressure could be taken off the law enforcement piece of it by basically taking the economic migrant out of the mix, then we'll be well on our way to getting effective control of the border," Rios said. "The majority of the folks that we apprehend are coming in for jobs."

"I think he's right on the money," said Angela Kelley, deputy director of the National Immigration Forum, a pro-immigration advocacy group based in Washington.

"What's needed is exactly what he (Rios) said, a comprehensive reform that takes those coming in illegally and putting them in legal channels."

Arrests of illegal immigrants from Texas to California have plunged 27 percent during the first four months of the current fiscal year compared to the same period in fiscal 2006 - from 308,400 to 230,469 - Rios said.

In Arizona, apprehensions fell by 9 percent in the Border Patrol's Tucson sector, for several years the nation's busiest for illegal immigrant traffic, and a dramatic 62 percent in the Yuma sector over the same four-month period.

For the fiscal year that ended Sept. 30, their apprehensions fell by 11 and more than 14 percent respectively.

Arizona accounted for 54 percent of the 1.1 million illegal immigrant apprehensions nationwide during fiscal 2004.

But not everyone agrees the numbers say things are going well.

T.J. Bonner, president of the Border Patrol agents' national union, said the decline in arrests could mean that traffic has dropped off, or they could mean the smugglers have moved elsewhere along the border where security isn't as tight. He said there's no way to know.

"For all the promise of technology, we still are not measuring the number of people crossing the border," Bonner said.

But Border Patrol agents in Arizona said the concentrated effort to beef up patrols, add technology and tactical infrastructure like fencing and vehicle barriers and the addition of thousands of National Guard troops is paying off.

"Putting the eyes and ears on the border is having an impact, and as we keep adding Border Patrol agents, it's all helping to decrease entries, it's a deterrent," Yuma Border Patrol spokesman Albert Bosco said. "It makes it less appealing for people to try to cross the border."

So does a downward trend in arrests mean that operational control of the border is at hand?

"We are moving in that direction," Rios said. "We still have a ways to go. But definitely more staffing, additional infrastructure and resources have contributed greatly to the downward trend."

"You can make some progress with enforcement alone, but ultimately you cannot control illegal immigration until you address the reality of our labor needs," said Tamar Jacoby, a senior fellow with the New York-based Manhattan Institute, a conservative think tank.

The government is doing a better job on the border "and that's to be welcome, applauded and something we should all be happy about," she said.

But gaining control will require realistically addressing the nation's labor needs, laws and work quotas, along with effective workplace enforcement including foolproof documentation that employers can rely on, Jacoby said.

"The guy in Ohio hiring is really the place that you're going to get control of the border," she said. "Because if you can't get a job without papers, people aren't going to bother to come."