Memphis, Louisville and Cincinnati — three of North America's largest air cargo gateways — are operating at or near physical capacity, opening a window for secondary airports to capture freighter traffic the primary hubs can no longer absorb.

What is GSP offering that the major hubs cannot?

Greenville-Spartanburg International Airport (GSP) in South Carolina is making the most concrete pitch. A new dedicated cargo area is under construction at the field, designed to separate freight from the passenger terminal, improve airside access, and give freighter operators the ground infrastructure needed for scheduled service rather than ad hoc charters.

GSP sits inside one of the densest automotive manufacturing corridors in the United States. BMW, Michelin, Volvo and hundreds of tier-one and tier-two suppliers are within trucking distance. The airport already handles automotive parts on a regular basis.

On top of the industrial base, GSP markets itself as a transshipment link between Canada and Latin America — a positioning that leverages runway availability rather than network reach. The bet is that uncongested operations and direct access to manufacturers will justify scheduled freighter calls the congested primary gateways can no longer accommodate.

Where does Harrisburg fit?

Harrisburg International Airport in Pennsylvania has its own cargo play. A planned 105,000 sq ft cargo facility targets freight that currently defaults to Philadelphia or Baltimore, both of which carry slot constraints and handling fees secondary operators describe as prohibitive.

The facility matters for three reasons:

• Lower airport fees and no slot restrictions make Harrisburg viable for smaller freighter operators.
• The Mid-Atlantic freight catchment supports e-commerce fulfilment networks that need reliability without gateway complexity.
• The 105,000 sq ft footprint gives integrators room to stage receiving that primary hubs cannot.

Why is the secondary-airport model working now?

Secondary airports have chased cargo for decades. Most of the time, the freight stays at the major hubs anyway. Three things are different in the current cycle.

Congestion at Memphis, Louisville and Cincinnati has moved from a turnaround-time nuisance into a service-reliability problem that costs airlines and forwarders measurable money. Hub delay now translates into missed overnight sort windows, and that shifts the routing math.

The European secondary-airport model has demonstrated the demand exists. Frankfurt-Hahn, Liège and Ostend have captured freighter traffic that outgrew Frankfurt, Brussels and Amsterdam respectively. Each operates as a specialized cargo gateway without the slot constraints of its parent hub.

E-commerce volumes are less route-sensitive than traditional express freight but highly cost-sensitive. That combination fits uncongested airports with regional manufacturing catchments — the exact profile GSP and Harrisburg are building toward.

What could still go wrong?

Capacity announcements at secondary airports have a long history of failing to convert into scheduled airline service. The barriers remain familiar.

• FedEx's Memphis Superhub and UPS's Louisville Worldport integrate sorting, customs and feeder trucking in ways that take decades and billions of dollars to replicate.
• Charter and ad hoc freighter operations generate revenue but rarely justify dedicated terminal infrastructure.
• Airline network planners require multi-year reliability data before committing aircraft and crews to a new field.

GSP's dedicated cargo area and Harrisburg's planned facility are still in development. The infrastructure question is partly answered. The harder question — whether integrators and freighters sign multi-year commitments — remains open. Secondary airports have won this argument on paper before. Converting it into runway tonnage is the test that follows.