Mexican cattle resume U.S. border crossings under screwworm safeguards

Reopening restores border trade while drought constrains U.S. cattle herds

Mexican cattle began passing through the Columbus, New Mexico, port on Monday after U.S. agriculture inspectors gave the crossing an all-clear. The movement ended a closure of nearly two years and made Columbus the third port to resume Mexican cattle imports under the bilateral safeguards developed to contain New World screwworm. Tests, shots and inspections occur before the cattle reach the border.

The reopening carries economic stakes for a $113 billion U.S. cattle industry. The closures cut off a source of cattle while the United States tries to rebuild drought-depleted herds, and containment efforts have cost jobs and trade in border communities. Reopening the ports could ease the supply squeeze, but experts cautioned that shoppers should not expect quick relief in beef prices.

The New World screwworm is a fly larva that burrows into the flesh of livestock, pets and even humans. It was an annual livestock scourge before the United States largely eradicated it in the 1960s. The parasite reappeared in Mexico in 2024, and the first confirmed U.S. case was in Texas in June.

More than 60 cases have since been confirmed in Texas and New Mexico, with infestations involving cattle, sheep, goats, horses and dogs. Last week, the first U.S. wildlife case was confirmed after a hunter found screwworm in an elk. Screwworm flies can also cross the border on their own, so ranchers, hunters and pet owners should remain vigilant.

The safeguards for imported cattle begin at their home ranches, where private veterinarians check for tuberculosis and other diseases and deliver medications that prevent screwworm. At the next stop, veterinarians accredited by the Mexican government look for open wounds, signs of illness and other injuries. The USDA then conducts a head-to-tail inspection while the animals remain in Mexico.

The final step is dipping, in which cattle are immersed in vats of insecticide to remove any parasites missed earlier. Officials and ranchers in both countries said the layered treatment and inspections give them confidence imported livestock will not carry screwworm through the ports. Dudley Hoskins, undersecretary for the Department of Agriculture, said, “As long as we can manage and mitigate that risk at an acceptable level, we will continue to process the safe and legal movement of cattle through these ports,” while watching cattle line up in the chutes at Columbus.

New Mexico is central to the reopened trade. About a third of all Mexican cattle imported into the United States each year pass through Columbus and the Santa Teresa port near El Paso, Texas. Gerardo Fierro, executive director of the New Mexico Border Authority, pegged the area’s cattle trade at $1 billion. He said the closures eliminated jobs, cattle sales and diesel-fuel tax revenue while ranchers stopped crossing into New Mexico and spending money on supplies, lodging and food. Farmers also lost customers for their alfalfa and grain. “This means a lot,” Fierro said of the reopening. Another border crossing for cattle in Arizona is due to open in late November.

Holeck said the protocols developed over recent years helped buy more time, and the USDA is using fly traps and drones to survey areas. The government’s longstanding program breeds sterile male flies and drops swarms from planes to mate with wild females, causing the flies to die out. The government is building a $610 million factory in Texas that can produce 300 million sterile flies per week, augmenting production at facilities in Mexico and Panama. “That’s our sharpest tool,” Hoskins said.

Before the current outbreak, the United States imported about 1 million head of cattle per year. Hoskins said it will take time to return to that level while monitoring animal-health risks. Mexican ranchers once again have a market for their feeder cattle, but U.S. ranchers are rebuilding herds that have fallen to record lows after years of persistent drought. Constrained supplies have pushed prices higher, and experts do not expect quick relief for shoppers.

Tom Paterson, president of the New Mexico Cattle Grower’s Association, met U.S. Agriculture Secretary Brooke Rollins in Columbus last week. Paterson said he agreed with Rollins when she said that “food security is national security.”