An exploratory analysis on the evolution of the US airport network

Airport network has a nontrivial impact on shaping the development of a country or region, and decision makers or researchers can benefit from its evolution characteristics. This paper presents an exploratory analysis on the evolution of the US airport network from 1990 to 2010. Generally, we find that (1) the USAN has experienced a drastic change in both its structure and traffic amount in the year 2002. Particularly, regarding the entire USAN, we show that (2) it preserves the scale-free, small-world, and disassortative mixing properties over time which is consistent with the previous studies. Thereafter, the evolution of the USAN is examined from two perspectives: stable cities that never disappear in the time period and new cities that only appear in certain years. Findings from the first perspective imply that (3) stable cities form the backbone of the USAN over time and their structural similarity over time shows regularity. On the other hand, results from the second one indicate that (4) the USAN is undergoing a process of continuous densification intertwined with intense exploration in 1991 and 2002, which consequently leads to a stable USAN. (C) 2014 Elsevier B.V. All rights reserved.