The US has been a pioneer w.r.t. the modern hub-and-spoke (HS) system which found near unequivocal support among aviation scholars over the last few decades. The author takes a more critical approach with regards to the central role that hub airports play within the ATS, particularly when assessing operational decisions that in effect may lead to highly skewed traffic distributions and increasing spatial concentration of air traffic. The behavior of airlines to organize traffic around central airports can be evaluated more meaningfully by differentiating for their constituent route-structures and comparing these ensembles for the largest airports in the entire system. A new understanding of behavior and evolution of the ATS as an aggregate of hub-driven networks can be obtained and alternative HS structures be compared. Our understanding of the scope of feasible hub strategies may expand beyond conventional strategies of 'consolidation' versus 'de-hubbing' and their impact on the overall ATS may plausibly be shown.