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Determinants of Airport Hubbing in the United States

This article examines the relationship between hub status of airports and their determinants. The factors governing the status of large hubs may not be the same as those determining the status of medium and small hubs. Using a binary logit model, the authors find that hubbing is more relevant in defining an airport than classifying a broader geographical area, for example, metropolitan statistical area. Results from their choice model defined over airport sample indicate that large hubs are qualitatively different than their medium- and small-hub counterparts. Thus, aviation activities captured in all hub airports as one continuous variable, for example, passenger enplanements, may not be appropriate for modeling purposes. An appropriate modeling may require grouping two or three broad categories of airports. Finally, their model determines an optimal size of the market that is presently served by hub airport. This finding has implications for both airport planning and future investment.