Eighty thousand cars a day pass through the immigration checkpoint at the south end of Temecula. And that means about 80,000 times a day a question gets asked: Why is this here, 70 miles north of the border?

I put this question to Sherry Feltner-Redondo, patrol agent in charge of the Temecula station since 1993. She has heard it many times before. As traffic has increased, so have critics who advocate closing the station -- including Congressman Darrell Issa of the 48th District.

"I know it's a pain to drive through the checkpoint," she said. "When people consider buying homes up here, they maybe go through it a couple of times and don't give it much thought. But then, every day... Well, it's like people buying homes by the airport. But we play an important role. If you're having a winning season, you don't remove your outfielders."

Athletic metaphors are apparently popular at the Temecula station. A while later, Rene Gonzalez, assistant agent in charge, said, "The Chargers wouldn't get rid of their defensive backs, would they?"

Whether outfielders or defensive backs, they've been part of the team for a long time. The Temecula and San Clemente stations, the busiest internal checkpoints in the nation, were established in 1924 to stop Al Capone's smuggling of liquor and Chinese workers. In those days, Highways 101 and 395 were the only routes running north and south.

Today there are more, of course, and that complicates matters.

"When I drove up here," I confessed to Agent Feltner-Redondo, "I exited at Rainbow Valley Road, easily driving around your checkpoint. And I followed a large paneled truck that, for all I know, was filled with 50 illegal aliens. Wouldn't any half-competent smuggler simply take an alternate route?"

"We keep them guessing. We randomly post agents on the alternate routes."

"I would think that if I were trying to sneak into this country, and I somehow made it across the desert of Imperial County, I could survive the wilds of Fallbrook."

"Yeah, the ones we catch must be pretty dumb, huh? Oops, did I say that? [She pointed to my tape recorder]. Forget I said that. If I had more agents and resources, I could do a better job. I've actually got ten checkpoints at this station -- six are what we call 'essential' and four are 'tactical.' But I just don't have the manpower to do it all."

"What happens to those you apprehend?"

"We read them their rights, then process them. We have a couple of holding cells here. If they're willing to go back, a bus picks them up."

"How many apprehensions do you make on an average day?"

"It varies." She seemed noncommittal, almost evasive. "One day it might be 12, another 2."

The Public Information Office of the Border Patrol says that in fiscal year 1995, the Temecula station apprehended 16,782; in fiscal year 2002 the number was 3256 -- an average of about 9 a day. This decline parallels the statistics for the region. The San Diego sector apprehended 556,231 in fiscal year 1995 but only 100,667 in fiscal year 2002.

Agent Feltner-Redondo attributed the drop to the increased presence of the Border Patrol following Operation Gatekeeper in 1994, which substantially increased personnel and resources. "In 1995 they kept coming," she said, "and they got caught. So by 1996 the decline started. It's a matter of deterrence. It's now tougher to get through, so fewer try it."

"Or, I suppose, the smugglers are more efficient."

"There's no way to know for sure."

To catch those nine illegal immigrants each day, the Temecula station employs 150 agents. They work eight-hour shifts, which usually expand a couple of hours each day because of overtime. Before they can stand between freeway lanes checking cars, they go through 20 weeks of training, taking courses in immigration and criminal law, firearm use, ethics and conduct, and Spanish (all agents are bilingual).

But experience is the best teacher. They watch carefully the reactions of thousands of motorists each day, and they learn to spot irregularities. Is he gripping the wheel too hard? Is she too cheerful? Is he too eager to give an answer? And they watch the eyes, especially the eyes, sometimes asking motorists to take off their sunglasses.

"My son-in-law is Latino," I told Feltner-Redondo. "Would he be more likely than I to be pulled over for further questioning?"

"No, not really. Racial profiling is an issue in most of the complaints I receive. People come to me and say, 'Why did you pull me over? I'm not even Hispanic!' "

"It must be difficult standing in the middle of traffic all day long."

"Well, they rotate that assignment. They're usually out there in half-hour shifts. The rest of the time they do administrative work and other things."

"I couldn't help noticing the plaque on the wall by the front door, the memorial to Agents Newton and Azrak, killed in the line of duty in 1967. It must be a constant reminder of the danger you face."

"We're aware of it. We have to stay alert, keep an eye on each other."

"What sort of weapons do you carry?"

"Berettas."

"How often have you had to use them?"

"Here, three or four times in the last ten years."

"Give me an example of when that was necessary."

"One guy jumped out of his car and started swinging a machete. Thought he was the Son of God. An agent shot him."

"Was he killed?"

"Just wounded. Whenever there's a shooting, I talk with the agent, get him into counseling. It's tough. There's always an investigation, to make sure everything was done properly."

"What was your own most harrowing experience?"

She paused, thinking. Then her eyes brightened. "I once took down 55 males by myself!"

"By yourself?"

"Yeah, and I wasn't even scared. I was too young to know any better."

Perhaps this would be the appropriate place to mention that Feltner-Redondo had been a professional roller-derby skater before joining the Patrol. I had the impression that she wouldn't have been easily intimidated on the track, or for that matter, anywhere else.

"How did you get that many?"

"I made them think I was scared."

"You wanted them to worry that you were so nervous you might pull the trigger?"

"Exactly. I got on the radio and called for help. 'You better get down here fast,' I said. They told me to march them out single file. 'Forget it!' I said. 'I'm not letting these guys up. Get over here.' Everything turned out fine."

Then, with a wistful tone to her voice, she said, "We used to arrest such nice people back then."

"Nice people? As opposed to today?"

"Yeah. Things have changed. I used to see a lot of calluses on the hands of the aliens, some were even carrying farm tools. They were coming for work. But today, there seems to be more of a criminal element."

"Drug smuggling?"

"Yeah, that. About one in ten of our apprehensions is for drugs."

To help uncover drugs, the Temecula station has ten sniffing dogs. They are assigned to agents who care for them as family pets in their homes. Most of those homes are in Temecula or the surrounding area. This is one reason it's a desirable assignment. Agent Gonzalez said that their agents tend to have high seniority in the Border Patrol.

"Is that because this is a good place to work?"

"It may not be as interesting as at the border, but it's a good place to live. A nice community for families."

I asked about one of his memorable experiences. He said he used to work in Chula Vista when many illegal migrants were running along the freeway. "It was really dangerous," he said, "and people were getting killed. Late one night I heard tires squeal and a thump, and I knew somebody had been hit. I ran toward the sound and found a body crumpled in the middle of the freeway. So I straddled it, and with a flashlight in each hand I waved down motorists. I didn't want cars, you know, to keep hitting him. I was almost hit a couple of times. It was really scary. And then I felt this movement between my legs. I looked down and saw he was crawling away. I said, 'What are you doing?' He said, 'I'm getting out of here!' And I said, 'That's a good idea.' "

As Agent Gonzalez told me this story, we were in one of their new GMC Yukons, heading from the Border Patrol office in Temecula toward the I-15 checkpoint. He was going to show me inside the trailers parked alongside the freeway, which house, among other things, a bank of video monitors enabling agents to watch stopped cars (when the wait goes over ten minutes, they shut down operations to allow traffic to "flush out"). Before we got to the checkpoint, though, we had to turn around to get in the northbound lanes. As we exited at Rainbow Valley Road, I thought again of alternate routes.

"Two or three times a year," he said, "we put agents on every alternate route, and then our apprehension rates jump about 500 percent."

Dr. Wayne Cornelius, director for the Center for Comparative Immigration Studies, UCSD, confirms my theory that smugglers have just gotten smarter. "Smugglers know how to get around the checkpoints," he said. "They take alternate routes, or they simply order their human cargo to start walking. They give them general directions about how they should navigate through the surrounding territory, and then they pick them up on the other side. With no cargo, there is no risk to them. This has been the standard MO for some time. The people they're likely to catch are the first-timers who simply don't have adequate information. In this day and age, it's inconceivable that anybody that's either experienced themselves or comes from a family in which one or more members have already migrated illegally would not know about those checkpoints."

I asked him why he thought the apprehension rates were down. "The Border Patrol claims it's the deterrence after Operation Gatekeeper. That's the crux of their argument. But they have absolutely no evidence for this. In fact, what's been happening is that traffic has been pushed farther and farther east. People are now crossing in Arizona, where apprehension rates are up. They're doing an end run around the San Diego sector and then making their way west. Also, apprehensions are down because the American economy is soft. The demand for migrant labor is down, and that's the main reason for the decline."

I mentioned Feltner-Redondo's observation that she had seen a change in the type of persons attempting to get across the border illegally.

"Listen," he said, "when I first began studying illegal Mexican migration to the United States, which was back in 1974, I was hearing the same arguments from the Border Patrol. The restrictionist groups are always claiming that in the good old days we had a better quality of immigrants. They always claim that the preceding cohort of migrants were easier to work with. They were always no problem, quiescent. And this talk about being infiltrated by a criminal element -- it's simply recycled.

"What has been the actual change? Yes, there have been fewer farmers coming, because there aren't as many farmers in Mexico. The bulk of the population of the migrant stream is now coming from urban areas. Nonagricultural backgrounds, seeking jobs in U.S. cities. So there are fewer people coming through with calluses on their hands and hoes over their shoulders. And the other big change is that there are children and whole families that are part of the flow, because so much of the migration is now for purposes of family unification, as well as women seeking their own employment opportunities on the U.S. side. What you've got is a more diverse flow. But there's no evidence that there's a higher percentage of people with criminal propensities today than there was a generation ago."

Agent Feltner-Redondo and Dr. Cornelius agree that the migrants are not the poorest of the poor, not people with starving families back home. They migrate not for survival, but to get ahead with better jobs. "As far back as the middle of the '70s," Cornelius continued, "when I started doing surveys of this population, there were as few as 5 percent who were unemployed at the time they migrated. They had some sort of work, but it wasn't enough to maintain a family or to maintain a decent standard of living; it wasn't enough to buy or build a house. And today there is between an eight-to-one and a ten-to-one wage differential between similar jobs in the U.S. and Mexico. For people to stay in Mexico and never try to enter the U.S. labor market, they're condemning themselves and their family to a substandard living."

According to Cornelius, controlling illegal migration through fortifications and increased manpower doesn't work; it won't change human behavior and alter the basic market forces driving migration. Broader social and economic issues must be addressed.

"Would you abolish the internal checkpoints?" I asked.

"Sure, they're relics. Whether they ever served a deterrent purpose is arguable, but they certainly don't now. They're only catching the most hapless people, and there are just too few of them to justify that deployment of manpower and resources, and the tip-off is that the politicians have abandoned them, and none of them are going to be soft on immigration."

Congressman Issa has sponsored legislation -- an amendment to a broader immigration bill -- to require the Attorney General to do a feasibility study of the internal checkpoints, and the bill now awaits action by the Senate.