A flesh-eating parasite closed the US cattle border for 15 months. The Aug. 24 reopening at one Arizona port turns a disease-control call into a fight over who gets the animals — and the high prices they carry.

A parasite set US cattle-trade policy for the past 15 months. On May 11, 2025, USDA suspended imports of live cattle, horses, and bison through every port of entry on the southern border, effective immediately, citing the northward spread of New World screwworm (NWS) in Mexico. The flesh-eating fly larva had been found on remote farms in Oaxaca and Veracruz, about 700 miles from the border. The block did not hold clean. USDA moved to reopen ports in a phased plan starting July 7, 2025. Two days later, on July 9, 2025, after Mexico reported a new case in Veracruz, Secretary Rollins shut the ports again, reversing the reopening that had just begun. On July 24, 2026, USDA announced a second phased reopening. Beginning Aug. 24, 2026, the Douglas, Arizona, port — which borders Sonora — reopens to cattle trade, with steps started toward later openings at Santa Teresa and Columbus, New Mexico. Every animal gets a full USDA inspection. The plan is conditional: it depends on Mexico following a joint US–Mexico action plan, "may be adjusted based on Mexico's progress," and "may be paused if USDA identifies increased risk in Sonora or Chihuahua". Mexican authorities set the flow at 700 head a day the first week, rising to 900, and up to 1,300 [reported — AP, citing a Sonora animal-health official]. The trade at stake is large. Before the closure, Mexico exported about 1.2 million head of cattle to the United States each year, worth about $1.2 billion last year [reported — AP]. During the block, Mexican ranchers sold into their home market "for nearly 40% less" than US prices [reported — AP]. The block landed on a tight market. As of Jan. 1, 2026, the US cattle herd stood at 86.2 million head — the fewest since 1951 — with beef cows at 27.6 million. Retail ground beef prices reached record highs through mid-2026 [reported]. As the reopening neared, Mexico reported 1,969 active screwworm cases, less than half of a year earlier [reported — AP]. On July 22, 2026, the closest active case to Douglas sat about 325 miles away. Days before the reopening, Sonora recorded its first screwworm case in decades. USDA said the Douglas date would not change.

The following is analysis, not fact. The screwworm decision was framed as animal-health containment, and on its face it is. But because roughly 1.2 million head a year move through these ports, closing them also removed a fixed slice of supply from a market already at a 75-year low. A quarantine line became, in effect, a supply valve — and reopening it re-opens that valve ^mmodeled. That is why "reopening" is not simply good news. It is a redistribution. The clearest read of the full picture is that two groups of American producers now want opposite things from the same gate. Feedlots near the border — especially in the Southwest — are built to buy and finish imported feeder cattle. Over the past decade, Mexican feeder cattle averaged roughly 5% of US feedlot placements, and those lots have spent 15 months sourcing from very tight domestic supply. For them, the cattle returning is relief. Cow-calf producers — the ranchers who raise and sell calves — sit on the other side. Record-low herd numbers and record-high calf prices are the direct result of scarcity. More imported animals, at the margin, add supply that can cap the very prices this group is finally capturing after years of drought and thin margins ^mmodeled. Neither group is wrong about its own economics. They are describing the same 1.2 million head from opposite ends of the chain. The phasing makes the trade-off explicit. Starting at 700 head a day is a fraction of the pre-closure flow. USDA is metering the return, which both limits the disease risk it is managing and limits the price relief importers want ^mmodeled.

Importers' side, steelmanned: the supply case is concrete and near-term. Feedlots with idle capacity and thin cattle supply face real cost pressure now; the 5%-of-placements figure understates the local dependence of specific Southwest lots that were built around this trade. On this view the reopening is overdue, and the daily caps are the binding constraint, not the disease. Cow-calf side, steelmanned: the scarcity that lifted calf prices is what is finally repaying producers after herd liquidation. Added imports, even metered, work against a price recovery they have waited years for ^mmodeled. This is a fear about direction, not a claim that 700 head a day floods the market tomorrow — the concern is the phased ramp toward 1,300 and beyond ^sspeculative. The strongest counter to reading this as a settled win runs through the parasite, not the economics. The reopening is explicitly contingent and reversible: USDA says it may be paused if risk rises in Sonora or Chihuahua. Sonora recorded its first screwworm case in decades days before the port reopened, and USDA held the date anyway. Whether that is disciplined risk management or a bet that outpaces the data is not resolvable from the public record ^sspeculative. If NWS keeps moving north, the same tool that reopened the border can close it again — and the animals, and the price effect, vanish with it.