As global trade continues its relentless march forward, with U.S. import values reaching record highs, a puzzling phenomenon has emerged: the number of shipping containers carrying these goods hasn't grown in tandem. What explains this growing divergence between import dollars and container volumes?
Over the past five years, U.S. total imports and maritime container throughput haven't always moved in lockstep. Recently, this disconnect has become particularly pronounced, driven by shifting port destinations and growing overland imports from Mexico. When excluding non-containerized goods like oil, automobiles, and trucks, U.S. imports have consistently exceeded $200 billion monthly for the past two years.
Meanwhile, U.S. port container imports peaked at 2.62 million twenty-foot equivalent units (TEUs) in May 2022—the standard industry measurement. While volumes remained relatively stable through August, September saw a dramatic 11.8% drop (305,000 TEUs). After brief stabilization in October, November brought another 11.6% decline before a modest December recovery. The annual total of 28.7 million TEUs represented a 1 million TEU decrease from 2021, though still well above pre-pandemic 2019-2020 levels.
The Great Disconnect
While the two metrics—import values and container volumes—have historically shown rough correlation, a clear divergence emerged starting March 2022. Import values surged dramatically while container throughput failed to keep pace, with the relationship recently turning negative. This presents an intriguing economic puzzle.
When considering imports, most envision container ships unloading at bustling ports. While not inaccurate, this represents only part of the picture. Over the past five years, maritime imports accounted for 43%-46% of total U.S. goods imports. Air freight—favored for high-value electronics and perishables due to speed despite higher costs—comprised 26%-30%. Overland imports from Canada and Mexico (via truck and rail) made up 27%-28%, creating a diversified import ecosystem.
The Port Shift Phenomenon
The pandemic's early days saw severe congestion at West Coast ports (Los Angeles/Long Beach, Oakland, Seattle), with 80-90 ships anchored offshore awaiting berths. While congestion eased intermittently, concerns about prolonged labor disputes accelerated two significant shifts.
First, container volumes increased at East Coast and Gulf Coast ports (Newark, Savannah, Norfolk, Houston, Charleston, Miami). Their share of total maritime container throughput grew by 6 percentage points since pandemic onset, exceeding 38%. Despite recent declines, February 2023 volumes remained strong at 41.5%.
Some port operators view this shift as permanent, partly due to the 2016 Panama Canal expansion accommodating New Panamax vessels (carrying 12,000-14,000 containers—2.5 times older Panamax ships). For certain shippers, direct Asia-to-East/Gulf Coast routes now prove more economical than West Coast arrivals followed by cross-country rail or truck transport.
Second, Laredo, Texas—not traditionally a "port" but long surpassing volumes of top-10 ports like Charleston and Miami combined—saw rising container flows. From April-July 2022, Laredo averaged 200,000 TEUs monthly via Mexico-U.S. border crossings. Investors increasingly bet this redirection represents a lasting change.
West Coast Congestion: Temporary or Structural?
West Coast port congestion served as the initial catalyst for diversion, but whether this represents temporary disruption or reveals deeper structural issues remains unclear. Infrastructure upgrades, labor relations improvements, and operational efficiencies could help West Coast ports regain market share. However, persistent challenges may cement the East/Gulf Coast shift.
The Panama Canal Factor
The expanded Panama Canal's ability to handle larger vessels has fundamentally altered shipping economics, enabling more cost-effective direct routes to eastern U.S. ports. While not universally applicable—due to capacity limits, toll costs, and certain cargo requirements—this infrastructure change has permanently reshaped competitive dynamics among U.S. ports.
Mexico's Manufacturing Ascent
Mexico's emergence as a nearshoring destination has driven overland import growth, with companies seeking shorter, more resilient supply chains. Laredo's prominence as a border crossing reflects this trend. However, Mexico faces its own challenges—security concerns, infrastructure gaps, and rising labor costs—that may constrain long-term potential.
The Hidden Variable: Import Composition
Shifts in import composition may also explain the value-volume disconnect. Increased imports of high-value, low-volume goods (e.g., electronics) or semi-finished components for domestic assembly could inflate import values without proportionally increasing container counts.
Building Supply Chain Resilience
The pandemic exposed global supply chain vulnerabilities, prompting companies to prioritize resilience over pure cost efficiency. Diversified sourcing strategies—including increased domestic production and nearshoring—may reduce reliance on maritime container imports while maintaining or growing total import values.
As with many pandemic-induced changes, only time will reveal whether these shipping patterns represent temporary adjustments or permanent transformations in global trade flows.