The US airline industry has experienced severe turbulence during the recent decade. The September 11 terrorist attack (9/11) was the greatest shock at the beginning of the 2000s. Recently, the dramatic increase in fuel costs emerged as another shock to the industry. To understand the effects of these two major events, this study investigated the cross-sectional efficiency of the US airline industry and its changes using the data envelopment analysis technique. The primary findings suggest that 9/11 affected the network carriers (NCs) more severely than the low-cost carriers (LCCs), while fuel costs more seriously influenced the LCCs than the NCs.