Greenville Spartanburg Int Airport (GSP) in Greer, South Carolina, United States has been in service since October 15, 1962, with national and international flight service, ... See more flying as many as serving 1,755,509 passengers in 2011. Prior to GSP, both Greenville and Spartanburg operated separate airports and would frequently compete for regularly scheduled airline service. The influence of Roger Milliken and other Upstate business leaders helped to create the vision of a shared airport facility between the two cities. In 1958, a proposal to build a shared airport facility between the two cities was presented to the legislative delegation for the two counties, which approved the construction and the creation of an airport commission headed by Milliken.