TIJUANA, Mexico -- In the mid-1980s, the border between Tijuana and Southern California was a showcase of America's failed immigration enforcement. On a busy night, thousands of people slipped into the United States illegally.
It was so easy to cross that gangs of Mexican thieves waited each night on Southern California hillsides, ready to prey on the migrants and occasionally to battle Border Patrol agents.
Now, the flow of migrants has become a trickle. Crime has plummeted. And the Border Patrol regularly conducts tours of its high-tech fence system for journalists, college researchers, congressional delegations and foreign military officials.
Even people who question U.S. immigration policies acknowledge that the 18-foot-high border barrier, topped with razor wire, has disrupted the flow of immigrants through Tijuana. Yet for all its effectiveness, Southern California's border can also help in understanding some of the less-than-perfect results.
"It's very effective," said the Rev. Pat Murphy, who runs Tijuana's largest shelter for deported men. "But so many people are deported. It divides families."
While the surge of Central American children crossing into Texas has rekindled the immigration debate, the Border Patrol in San Diego says it has seen no onslaught of children. On the Tijuana side, shelters that house children say they have seen no significant numbers of the Central American youths.
In the 1980s, much of Tijuana and Southern California was separated only by strands of heavy steel cables that were supposed to deter off-road vehicles from shuttling migrants and drugs north. They did little to stop foot traffic.
At that time, the Border Patrol's San Diego sector was catching 500,000 to 600,000 illegal immigrants a year, more than a third of all illegal immigrants caught on the entire 1,950-mile border.
In fiscal 2013, 27,496 were caught in the sector, less than 7 percent of national total.
The San Diego sector is just one of many that has been upgraded. About 175 miles to the east, for example, a flood-lit, multilayered fence divides Yuma, Ariz., and San Luis Rio Colorado. The Yuma sector also has experienced a dramatic decrease in apprehensions.
The California border barrier -- composed of dual fences with an access road between them -- splits the sparsely inhabited hills of San Diego County from Tijuana's working-class La Libertad neighborhood.
When I first visited La Libertad in the 1980s, it was one of the primary illegal entrances to America.
North of La Libertad, the border had almost ceased to exist. On a busy night, as many as 5,000 people, mainly Mexican migrants, gathered on an open field on the U.S. side before sunset, preparing to run toward San Diego. And Mexican thieves regularly stationed themselves in hills on the U.S. side to rob the migrants as they passed.
In one of the many contradictions of enforcing immigration law, the Border Patrol would send special teams to meet with the migrants in the field and warn of the most dangerous canyons and gullies. Although the agents' job was to catch illegal immigrants, no one wanted them to be crime victims.
Not until 1991 did the U.S. Army Corps of Engineers start building an 8-foot-high metal wall constructed from Vietnam War portable landing pads. It now runs for 46 miles. Later came the tall fence and stadium-style lighting.
In Tijuana, a city of 1.3 million, it's easy to see the results of stepped-up U.S. enforcement. Adults break down crying when they talk about being separated from their U.S.-born children.
"Deportation is almost like going through death," Murphy said at Casa de Migrante, which has been operating for 27 years.
Ignacio Jaimes, 42, one of the deportees at Casa de Migrante, said life as he knew it for nearly three decades in suburban Los Angeles ended when he was deported in June.
Jaimes first entered the United States illegally in 1987, working construction jobs in the Los Angeles area and raising a family. He sent three children to college, including a stepson who is now a doctoral candidate at Massachusetts Institute of Technology.
Jaimes was arrested in 2008 for drunken driving and was picked up on an old warrant. He said he had no chance to contest deportation before he was put on a bus to the border and shuttled through a metal gate into Mexico.
Jaimes, losing control of his emotions, tried to explain the distress his deportation caused for his family, especially his daughter, 21.
"My daughter, she cut herself" he said, choking back tears and passing his finger across his wrist to demonstrate.
Jaimes said he spoke with her after learning of what she did and assured her that their family would somehow work through its current problems.
For others separated from their families, there is a meeting place called Friendship Park, on the U.S. beach at the Pacific end of the border, before the fence pokes up from the ocean to block immigrants from entering by swimming.
The park was inaugurated in 1971 by then-first lady Pat Nixon. It was seen as a symbol of binational friendship, and Nixon bluntly declared then that "I hate to see a fence anywhere."
Of course, the fence will be part of the border for the foreseeable future.
Each weekend at the park, divided families talk through the barrier. It's the only way they can see relatives face to face.
On the U.S. side, the thick steel border beams are unscarred. On the Mexican side, graffiti denounces the fence. A group of Mexican citizens who served in the U.S. military but were deported have painted murals, include a huge upside-down American flag, with crosses replacing the stars.
But for families, it can be a place of sharing, and typically tears. Each Saturday and Sunday, the Border Patrol opens the park for four hours. The Tijuana side is open 24/7.
Elderly Mexicans come to see their U.S. grandchildren, U.S.-born children see their deported parents, and there have been marriage proposals through the fence.
U.S. and Mexican park supporters fought long battles to ensure that it stayed open, despite the constant upgrades in security. They say the park is a humanitarian effort that works.
For the Border Patrol, it is a recognition of the reality of two nations divided, with people pushed apart.
"We don't know the immigration status," agency spokesman Timothy Hamill said of the park visitors. "We offer it as a courtesy. We're not checking ID when they come down here."