The mechanism. The Panama Canal runs on rainfall, not seawater — every transit through the Gatun and Miraflores locks drains millions of gallons of fresh water from Gatun Lake, the same reservoir that supplies drinking water to Panama City. When the 2023-2024 drought — the worst in the canal's recorded history — cut rainfall roughly 43% below normal, the Panama Canal Authority (ACP) slashed daily transits from a typical 36-38 ships to as low as 22 and imposed draft restrictions that forced containerships to sail lighter or wait weeks for a slot. The U.S. Army Corps of Engineers has maintained a standing technical-assistance relationship with the ACP on watershed and reservoir management for decades, and State Department engagement around canal reliability intensified as the drought threatened a trade artery carrying roughly 40% of U.S. container traffic. The fix that actually shipped cargo, though, wasn't more rain — it was rerouting. Shippers and carriers leaned harder on the West Coast port complex plus transcontinental double-stack rail, the classic "mini land-bridge" alternative to an all-water Asia-to-East-Coast transit. Even as La Niña restored full 50-foot draft through 2025 and into 2026, the ACP itself is now warning that a resurgent El Niño could tighten water availability again — meaning shippers who rebuilt West Coast-rail routings as insurance have little incentive to unwind them. Durable hedges rarely get torn back down once they're built.

Who cashes in:

  • Union Pacific (UNP) is the direct beneficiary of any Asia cargo that lands at Los Angeles/Long Beach, Oakland, or Seattle-Tacoma instead of transiting the canal to Savannah or New York-New Jersey. UP's network is the dominant rail bridge from West Coast ports to Midwest and Gulf inland points, and every box that stays on steel wheels instead of a canal transit is incremental haul-length revenue that has nothing to do with tariff policy.
  • Matson (MATX), the premier expedited carrier on the trans-Pacific to Long Beach/Oakland, benefits structurally from shippers prioritizing speed and reliability into West Coast gateways over canal-transit uncertainty — its niche is exactly the fast, capacity-guaranteed lane that canal drought risk makes more attractive.
  • XPO (XPO) and other West Coast-adjacent intermodal drayage and brokerage networks pick up incremental volume any time container flow shifts toward the LA/Long Beach-to-rail corridor rather than direct East Coast discharge.