Since the advent of air travel, airlines have regularly fallen apart and been put back together by government and the courts. Whether through mergers and acquisitions or bankruptcies, the industry regularly reconfigures and reinvents itself. Here are some of the more noteworthy bankruptcies in the U.S. in recent years: Frontier (2008); ATA (2008); Delta (2005); Northwest (2005); US Airways for the second time (2004); United (2002); US Airways (2002); TWA for the third and last time (2001); Pan Am for the second and last time (1998); TWA (1995); TWA (1992); Eastern (1991); Continental (1991); Pan Am (1991). On the merger side of things, some recent ones include Southwest/Air Tran (2011), United/Continental (2010), Delta/Northwest (2008), US Airways/America West (2005), and Air Tran/ValuJet 1997.1