The debate over how to control America's borders has been long on rancor and short on basic facts. Congress would do well to slow down and listen to what experts who have studied the problem have to say.

Both the Senate and the House are clamoring to hire several thousand new border agents and build hundreds of miles of fences. They seem to have joined in a quasi-"arms race" to see who can throw more money at border control.The escalating spending numbers have become a bumper sticker for bragging rights over which chamber is more serious. The only thing Congress hasn't been serious about is considering how their proposals actually will affect immigration - and emigration.

If Congress had looked at the academic research, it might have had second thoughts. According to a study by Dr. Manuela Angelucci, an economist at the University of Arizona, each additional border patrol agent hired will stop roughly 771 to 1,621 illegal border crossings annually. That sounds pretty impressive. But then, several hundreds of thousands illegally cross the border every year.

But that's only half the story. Each additional agent hired, studies find, encourages roughly 831 to 1,966 illegal immigrants already in the United States to stay here, out of fear of being caught at the border if they try to go home.

"The effect of an additional agent," concluded David Muhlhausen, who reviewed the academic studies in a report for the Heritage Foundation, "is unclear, possibly resulting in a net reduction of 503 individuals or a net increase of 995 individuals residing in the United States illegally."

If this research is right, Congress is pushing for a solution that has as much a chance of making the problem bigger, not better.

Mr. Muhlhausen cites additional findings that indicate hiring additional agents is no cure-all. "Other studies," he notes, "indicate that illegal immigrants are very intent upon crossing the border. Virtually no sanctions (e.g., fines, detention) are imposed on apprehended illegal immigrants by the federal government.

Because there is little or no cost to being apprehended by the Border Patrol, the research suggests that illegal immigrants will make as many trips as necessary to successfully cross the border."

The congressional focus on manpower and fences ignores another key fact: About half of the illegal immigrants currently in the United States came here legally. They had a visa and simply stayed when it expired. Border security doesn't stop them. And the more secure the border gets, the more likely it is that we'll see even greater abuse of visas and an exponential increase in the trafficking of phony visas and other identity documents.

It's a paradox: Heightened border security can produce a net increase in illegal immigrants. Yet many in Congress seem to have no appetite for doing anything other than spending money on border security.

Border security efforts must be backed by "interior" policies that make illegal immigration a less attractive option:

• For starters, Congress shouldn't reward people for breaking the law. That means no amnesty for those already here. Illegal immigrants who want to reside here legally should be required to return to their country of origin and then come back through legal channels.
• There should be no "catch and release." Anyone caught here illegally must be detained and deported.
  
• We need sensible workplace enforcement. The feds should go after big companies that intentionally hire illegals to secure big profits.
  
• End the loophole known as "birth-right citizenship," a flawed reading of the Constitution that grants citizenship to children born here even though their parents entered the country illegally.
  
• Congress should move to create a lawful program for those who want to come to this country to work for a limited time, and then go home. A temporary work program must allow only truly temporary work. People who want to come here and stay permanently should follow a traditional path to citizenship.
  

In short, we need security combined with deterrence and legal alternatives to control our borders and reinforce the rule of law. A one-dimensional "seal the borders" approach will be far more costly and doomed to fail.

Let's ditch the bumper stickers - and go with what works.

James Carafano is senior fellow at The Heritage Foundation and co-author of "Winning the Long War: Lessons from the Cold War for Defeating Terrorism and Preserving Freedom."