DFW is the nation's 2nd largest airport in terms of space (behind Denver). its operations lag at #3 in the world behind Atlanta (Delta Hub) and Chicago (AA and UA hub). DFW is an excellent O & D airport with its unique half-circle terminals. As a hub airport, it can lead to long walks. The 4 original terminals, from the January 1974 opening, are being remodeled in and out with the addition of an elevated People Mover train system to replace the subterranean Tram systerm. An international terminal, Terminal D, opened in late 2005. It was about the worst place in the country to photograph ramps, aircraft, and terminals until the arrival of the new overhead trains which provides excellent opportunities. DFW is the headquaters and main hub of American Airlines, since 1981, replacing hometown carrier Braniff which liquidated initally in 1982 and then deserted the DFW hub by 1987 in its second carnation. Delta, who once used DFW as a focal point between east and west coast services, operated a long-time hub following the liquidation of Braniff but abandoned it in February 2005. Delta's Terminal E is seen here.