within the United States. British Airways later briefly flew Concordes to Dallas in 1988 as a substitute for its ordinarily scheduled DC-10 service. Following airline deregulation, American Airlines (which had already been one of the largest carriers serving the Dallas/Fort Worth area for many years) established its first hub at DFW on June 11, 1981. American finished moving its headquarters from Grand Prairie, Texas, to a building in Fort Worth located on the site of the old Greater Southwest International Airport, near DFW Airport on January 17, 1983; the airline began leasing the facility from the airport, which owns the facility. By 1984, the American hub occupied most of Terminal 3E and part of Terminal 2E. American's hub grew to fill all of Terminal 2E by 1991. American also began long-haul international service from DFW, adding flights to London in 1982 and Tokyo in 1987. Delta Air Lines also built up a hub operation at DFW, which occupied most of Terminal 4E through the 1990s. The Delta hub peaked around 1991, when Delta had a 35% market share at DFW; its share was halved by 2004, after many of its mainline routes were downgraded to more frequent regional jet service in 2003. Delta constructed a satellite terminal in Terminal E in 1988 to accommodate their hub, which was permanently reopened in May 2019 for American Eagle operations. Delta closed its DFW hub in 2004 in a restructuring of the airline to avoid bankruptcy, cutting its DFW operation to only 21 flights a day from over 250 and redeploying aircraft to hubs in Cincinnati, Atlanta and Salt Lake City. Prior to the closure, Delta had a 17.3% market share at DFW. In 1989 the airport authority announced plans to rebuild the existing terminals and add two runways. After an environmental impact study was released the following year, the cities of Irving, Euless and Grapevine sued the airport over its extension plans, a battle that was finally decided (in favor of the airport) by the US Supreme Court in 1994. The seventh runway opened in 1996. The four primary north-south runways (those closest to the terminals) were all lengthened from to their present length of . The first, 17R/35L, was extended in 1996 (at the same time the new runway was constructed) and the other three (17C/35C, 18L/36R, and 18R/36L) were extended in 2005. DFW is now the only airport in the