Capacity, Not Demand, Is Tightening Cross-Border Freight, and Diesel Is Sending It to Rail
Moving freight across the U.S. borders with Canada and Mexico has become measurably harder over the past several months, and the pressure is coming less from a surge in shipments than from a shortage of trucks to haul them. The NAX Index for June 2026, a cross-border barometer published by the logistics company TRAFFIX, reads 55 for the Canada corridor and 51 for the Mexico corridor, both sitting above the 50 line that separates loosening conditions from tightening ones, and both have held there since conditions turned earlier in the year. A score above 50 points to higher costs, scarcer capacity, and heavier regulatory friction, and neither corridor has slipped back under it.
The index blends roughly eleven economic, freight, and trade indicators into a single score for each corridor, and the breakdown behind the June reading points to one pressure above the others. Capacity has moved well above 50, which means available trucks have grown harder to find and that bookings now take more planning and lead time. Demand, by contrast, has stayed close to 50, with shipment volumes holding steady rather than climbing, so the tightness is not a case of freight outrunning the fleet. Cost has drifted upward again, driven mainly by fuel and by how carriers are setting rates, while policy remains the least predictable of the four, as tariff activity and shifting trade rules keep clouding cross-border planning and pricing. Canada lanes are tighter than Mexico lanes at the moment, especially around truck availability and scheduling.
Fuel accounts for most of that cost pressure, and the national average price of on-highway diesel stood at $5.21 a gallon in the week of June 8, according to the Energy Information Administration, down for a fifth straight week from an early-May peak near $5.64, yet still roughly $1.74 above where it sat a year earlier. The climb began in late February, when the closure of the Strait of Hormuz cut off a waterway that carries about a fifth of the world’s petroleum and sent distillate prices sharply higher across North America. Federal forecasters expect traffic through the strait to resume during the third quarter, which would pull diesel down further, though their own projections keep the 2026 average well above pre-conflict levels.
High diesel reliably pushes freight toward the railroads, and 2026 is following the pattern. U.S. intermodal rail volume rose 8.1 percent in May from a year earlier to a record level, the fourth straight monthly gain reported by the Association of American Railroads, and carriers describe a clear move among shippers looking to take fuel exposure off the road. That shift was slower to arrive than the fuel math alone would suggest, because earlier in the year J.B. Hunt told investors that the run-up had not yet moved much truck freight to rail, since shippers did not believe energy prices had changed for good. By the start of summer the hesitation had faded, and C.H. Robinson reported accelerating conversion on lanes of roughly 550 to 1,500 miles, the middle-distance freight where rail competes most directly with a truck. J.B. Hunt itself posted record first-quarter intermodal volume and said its network could absorb meaningfully more, which means the rail capacity exists to carry the freight that high diesel is pushing off the highway.
The economics behind that move are straightforward at current prices. Intermodal has been running roughly 23 percent cheaper than comparable truckload service this spring, a wider gap than the ten to fifteen percent that prevailed before fuel climbed. Diesel also falls more heavily on trucking than on rail, since fuel makes up about a fifth of the cost of operating a truck for every mile by the American Transportation Research Institute’s most recent accounting, a share that rises as prices climb, while a train moves a ton of freight on a fraction of the fuel a fleet of trucks would burn over the same distance. TRAFFIX makes the same point in its own guidance, advising shippers with flexible delivery windows to route longer cross-border lanes through intermodal rail where timing allows.
Cost and capacity are only part of what makes cross-border planning difficult this year, because trade policy keeps moving the ground beneath it. A ten percent surcharge applied under Section 122 of U.S. trade law is set to lapse around July 24 unless Congress extends it, and the first formal review of the U.S.-Mexico-Canada Agreement is scheduled for July, with rules on regional content the central question. Neither outcome is settled, which leaves importers and brokers pricing freight against rules that could change inside a single quarter. Demand on the Mexico corridor has held strong through all of it, with cross-border trade reaching record levels at Laredo, which now ranks as the busiest land port in the hemisphere, and nearshoring continuing to pull manufacturing south, while Canada lanes have tightened partly on stricter enforcement that has thinned the available carrier base.
For shippers, the practical response is the one the index recommends: build in more lead time, lock down truck capacity earlier than usual, and move the freight that can tolerate a longer transit onto rail. Diesel may keep easing if the Strait of Hormuz reopens on the timeline forecasters now expect, which would narrow rail’s advantage and relieve some of the cost pressure, though prices would still sit above where they were a year ago. What the June reading describes is a market held tight by scarce trucks rather than booming demand, and that distinction matters for anyone planning the next quarter, because capacity shortages ease on a different clock than demand spikes, and they reward the shippers who secure trucks and lock lanes well before the freight has to move.
Sources
U.S. Energy Information Administration — Short-Term Energy Outlook
FreightWaves — J.B. Hunt says fuel spike not yet driving intermodal conversion
C.H. Robinson — North America Freight Market Update, June 2026
Commercial Carrier Journal — Diesel prices are driving shippers to intermodal
American Transportation Research Institute — 2025 Operational Costs of Trucking
FreightWaves — USMCA review tests China’s growing role in Mexico supply chains
Bureau of Transportation Statistics — Transborder Freight Data Annual Report 2025
