There has been turbulence along the way, but certainly airline alliances have made earning miles more possible for any far-flung destination you can think of. Not all major carriers are in alliances, but many are. I name Star Alliance, not just because of its earlier start date, but because it went from five founding members to over two dozen by the end of 2009. Oneworld came together in 1999, SkyTeam in 2000. This growing trend should continue well into the next decade.
