Hartsfield–Jackson Atlanta International Airport now the airport's second largest carrier. In May 2001 construction of an over fifth runway (10–28) began. It was completed at a cost of $1.28 billion and opened on May 27, 2006. It bridges Interstate 285 (the Perimeter) on the airport's south side, making Hartsfield–Jackson the nation's only civil airport to have a runway above an interstate (although Runway 17R/35L at Stapleton International Airport in Denver, Colorado crossed Interstate 70 until that airport closed in 1995). The massive project, which involved putting fill dirt eleven stories high in some places, destroyed some surrounding neighborhoods and dramatically changed the scenery of
Denver International Airport Stapleton International Airport, and there was also a significant Southwest Airlines operation. At times, Stapleton was a hub for three or four airlines. The main reasons that justified the construction of the new DIA included the fact that gate space was severely limited at Stapleton, and the Stapleton runways were unable to deal efficiently with Denver's weather and wind patterns, causing nationwide travel disruption. From 1980 to 1983, the Denver Regional Council of Governments (DRCOG) investigated six areas for a new metro area airport that were north and east of Denver. In September 1989, under the leadership of Denver Mayor