The route northward passes through El Naranjo, a Guatemala jungle town where I rode in a little boat that puttered along the flat water of the Umacinta river, past tall ceiba trees and the largely apathetic Mexican border patrol.
And it ends in places like Compton, where there's a white stucco box of a house with the roof painted ominously black and bars on the windows. Until recently, two quiet Latinos lived there, waving to the neighbors and barbecuing on the front lawn while they held more than two dozen people hostage inside.
This is the trail immigrants follow to enter the United States illegally. It's more than 2,000 miles long, and crazy things happen at nearly every stop.
In my years as a foreign correspondent for The Times, I walked small stretches of the route -- on the abandoned railroad tracks of Tenosique, Mexico, and in the rail yards of Ecatepec, just outside Mexico City. I've seen vistas of great beauty -- the Sonora desert, for example, and the rust-colored hills south of Tombstone, Ariz.
The people you meet at these places have left behind families in the villages and cities of Central America and Mexico. They are desperate, self-deluded and courageous all at once. Those qualities make them pure gold for corrupt officials and various criminal enterprises, big and small.
They pay small bribes or "fees" to boat operators, local "guides," truck drivers and policemen to pass through Mexico. And then thousands of dollars to smugglers who say they can get them around the high-tech obstacles at the U.S. border. Those smugglers are transforming the trail into a journey of intimidation and horror.
The mostly black residents of Dern Avenue in Compton got to witness the chaotic end to one of these journeys last week.
"I've seen a lot of strange things on this block -- I've seen people shot," a young musician told me. "But I've never seen anything like that."
The stucco box was a drop house for immigrant smugglers. The people inside -- about 30 residents of Guatemala, El Salvador and Ecuador -- had already paid thousands of dollars to get as far as Compton. Now the smugglers were demanding more money from their families.
They were locked in three rooms and held at bay by a pit bull, according to agents with Immigration and Customs Enforcement. Their ranks included two boys from Ecuador, ages 7 and 9.
None of the neighbors had any inkling what was going on. The two guys renting the house seemed normal enough. "They were friendly," said Alma Jackson, 60.
They mowed the front lawn and even had a Fourth of July barbecue in the frontyard, though Jackson noted: "It sure seemed like they were cooking a lot of food for just two people."
Then, on July 27, the musician was sitting on the porch across the street when he saw a woman pulling back at the curtain. "I thought it was a little game they were playing, like hide and go seek." When she started gesturing frantically, he walked across the street.
She threw out a piece of toilet paper with words written in Spanish. Unfortunately, the musician didn't read the language. "I could make out some words, like 'policia,' " he told me. He took the note to a Mexican family that lived nearby.
We're trapped inside this house, the note said. It gave a phone number for a U.S. relative to call for help. It also said: "Do NOT call the police." But someone decided to call the police anyway.
When Los Angeles County sheriff's deputies arrived, the smugglers set loose the pit bull. The deputies shot the animal, as the hostages and smugglers sprinted out the doors and into the streets and alleys.
About a dozen people escaped into the dying heat of the late afternoon. They ran over crab grass lawns and into backyards, toward Avalon and El Segundo boulevards, disappearing into the city, seeking some Spanish-speaking person who might help them.
The Sheriff's Department detained three suspected smugglers -- including one who bit a deputy on the leg --and turned over 17 people to immigration authorities.
A television crew entered the home and found a horrid stench of feces. Blood covered the floor of a bathroom where the wounded pit bull died. "The sheriffs pulled a rifle out of there too," one resident said. Like the pit bull, the weapon was probably used to control the people inside.
The Ecuadorean boys were found hiding in a nearby abandoned house, residents said. One managed to tell them his story before the immigration authorities took him away.
"He said he was trying to get to his mother in New York," Jackson told me. "I do hope he sees his mother again."
Jackson, a retired county employee, was shaken by what she had seen and heard. Her family moved to Compton in 1950, and was one of the first to integrate the mostly white block, she said. She grew up with Asians and Latinos, and had always thought of Compton as a place of opportunity. Now she's seen her neighborhood drawn into something evil.
The dark episode ended with the clanking of handcuffs as the immigration authorities led the detainees away.
"When I heard those chains, I shed a tear," Jackson told me. "Thinking of them being hungry and needy. It took me back to what we know, as blacks."
I told her about some of the things I'd seen on the trail: the river in Guatemala, the men who planned to walk 200 miles down abandoned railroad tracks in Mexico and the sunburned man and his teenage daughter I met just south of Naco, Ariz. "It's horrible when you think of the large scale of things," she said. "I had no idea this was happening."
Few immigrants realize that the thousands of dollars they pay to smugglers are just the down payment toward a larger ransom. Smugglers have been known to starve or maim their hostages to get more money out of their families, said Tracy Cormier, an assistant special agent in charge for the ICE in Los Angeles.
The bigger the illicit profits, the more dangerous the criminals. Our Border Patrol agents live with this reality every day: On Friday, they buried one of their own, Agent Robert Rosas, who was killed by suspected smugglers near Campo, Calif.
Violence is becoming the defining trait of an illegal-immigrant trail that already denigrates and humiliates the people who choose to undertake it. It's an outrage that so much of the U.S. economy continues to feed off their suffering.
The existence of this human trade is a stain on American democracy. And I use "American" in the broadest sense of the word, because leaders in Washington, Mexico City, Tegucigalpa, San Salvador and Guatemala City all share the blame.