Police officers work on a crime scene on July 23 after eight people were found dead inside a sweltering tractor-trailer parked behind a Walmart store in San Antonio. Two more people died later in a hospital. (Ray Whitehouse/Reuters)

THE TABLEAU of misery inside a tractor-trailer packed with undocumented immigrants at a Walmart parking lot in San Antonio last weekend was beyond horrific. At one point, before dozens of the migrants were offloaded by human traffickers, more than 100 people — possibly many more — were crammed into the trailer’s lightless, nearly airless interior, baking in the South Texas summer heat and taking turns to suck air through a hole in the vehicle’s side. By the time police were summoned, early Sunday, eight people lay dead inside the trailer; two more died in the hospital in the ensuing 24 hours. Many others, having succumbed to heatstroke and related afflictions, suffered grievous injuries.

This unimaginable spectacle of suffering was the product of desperation on the part of the immigrants for better economic circumstances and callous criminality on the part of traffickers. The carnage in the Walmart parking lot was neither the first nor even the worst such incident. In 2003, 19 undocumented immigrants, including a 7-year-old boy and a 91-year-old man, were found dead from heat and asphyxiation in the back of a truck in Victoria, Tex.

It is to be hoped that state and federal authorities will sweep up the traffickers responsible for this outrage in San Antonio and that sentences will be harsh. (The truck driver, James Matthew Bradley Jr. of Florida, is in custody. He denies having known that people were locked in the truck before arriving at the Walmart and hearing banging and shaking in the trailer, according to the criminal complaint filed in federal court. Inexcusably, he apparently failed to call 911 even after discovering the bodies.)

The magnetic pull of the U.S. economy and its demand for low-wage, low-skilled labor has for decades attracted poverty-stricken workers from south of the border willing to take inordinate risks and enter into bargains with unscrupulous smugglers.

The Trump administration, so far at least, has managed to drive down the number of illegal border crossers, partly by toughening actual enforcement but mainly by jawboning — establishing an inhospitable political environment. Undocumented immigrants, said Thomas D. Homan, acting director of Immigration and Customs Enforcement, “should be afraid.”

But not all have been or will be dissuaded. In Texas in just the first week of this month, Border Patrol agents came upon 72 illegal immigrants locked inside a tractor-trailer, unable to escape. Nineteen more, in two separate incidents, were spotted lost in ranchlands in searing heat. And 10 others were found inside a tractor-trailer at an inspection checkpoint. All that was just a snapshot of activity from the Border Patrol’s Laredo Sector.

Those undocumented immigrants were the lucky ones, discovered in good health. Without an overhaul of the nation’s dysfunctional immigration laws, don’t expect illegal immigration or human trafficking or further terrible tragedies to end anytime soon.