Passenger and Freight Traffic at North American
The North American passenger and freight air transport
system is designed around the hub-and-spoke network structure.
There is a significant divergence between the activity level of
passenger and freight airports. The activity level of passenger
airports is related to the distribution of the population with
airports having a higher activity level either because they are
the hubs of major airlines or are important resort areas (e.g.
Las Vegas, Orlando). For instance, Delta mainly operates hubs at
Atlanta (ATL), Detroit (DTW) and Minneapolis (MSP), while United
mainly operates hubs at Denver (DEN), Houston (IAH), Chicago
(ORD), Los Angeles
(LAX) and Newark (EWR). American Airlines mostly operates hubs
at Dallas-Fort Worth (DFW), Chicago (ORD) and Miami (MIA).
The activity level of freight airports
has two dimensions. The first concerns the major commercial
gateways of North America (e.g. New York, Miami, Los Angeles,
Chicago, Toronto), which are at the same time major consumption
markets. The second concerns the hub-and-spoke strategies of air
freight integrators. The Midwest being the demographic and
economic centroid of the United States, many air freight
integrators have located their hubs at airports such as Memphis
(Federal Express) and Louisville (UPS) that generate substantial
cargo flows, but little passenger traffic.