American International: Latin America (from Miami, Dallas), Caribbean (from Miami, San Juan), Europe (from Chicago-O'Hare, New York-JFK
, some other cities).
------------Notably weak in Asia besides some Tokyo routes and some other spot flights. Absent from Australia.
American Domestic: Transcontinental routes (mostly involving New York-JFK
), South-central part of country, Southern Great Plains, and routes involving Dallas-Fort Worth, Chicago-O'Hare, New York-La Guardia, etc.
------------Notably weak in much of western U.S. outside of California, and in Southeastern U.S. outside of Miami.
United International: Asia (from Los Angeles, San Francisco, Chicago-O'Hare), some Europe (from Washington-Dulles, Chicago-O'Hare). Only major U.S. airline to serve Australia.
------------Notably weak in Latin America.
United Domestic: Transcontinental routes, especially running across an axis of Los Angeles/San Francisco, Denver, Chicago-O'Hare, and Washington-Dulles. Also generally strong west of the Great Lakes except for Texas area.
------------Notably weak on east coast (except Dulles). Also weak in Texas, southeastern US.
Delta International: Very strong in Europe (from New York-JFK
, Atlanta, some Cincinnati), also good presence in Caribbean/Latin America (Caribbean from Atlanta, Latin America from Atlanta and Los Angeles).
------------Notably weak in Asia, absent from Australia.
Delta Domestic: Strong network, but strongest in Southeastern U.S. and Florida. Runs widebodies to most major Florida cities from Atlanta. Cincinnati also reinforces Southeastern service. Strong on East Coast in general. Improving west coast prescence - has SLC
hub, but also is growing service at LAX
to many western cities.
------------Notably weak in Central U.S., especially after they closed their DFW
hub a couple of years ago.
Northwest International: Very strong in Asia, where it runs its own hub at Tokyo-Narita. Also has a strong European network through Amsterdam due to a very strong KLM partnership.
------------Notably weak in Latin America and Caribbean, except for wintertime flights to vacation destinations. Doesn't have much of a transatlantic network outside of Amsterdam and some of the biggest cities in Europe. Otherwise a minor player on the Atlantic. Absent from Australia.
Northwest Domestic: Very strong in Central U.S., where all of its U.S. hubs are located. Strongest part of that is the North Central U.S., where it is dominant in Montana, the Dakotas, Minnesota, Wisconsin, and Michigan. Flights to Seattle are strong flights, although NW
doesn't hub there. Decent Hawaiian prescence.
------------Notably lacks north-south flights on both coasts, especially the west coast where its partnerships are minimal.
Continental International: Very strong in Europe where it runs flights from its New York-Newark hub. Also strong in Latin America, from its Houston hub. Some Asian presence but not very much - but does serve Oceania well with Continental Micronesia.
------------Not very strong in Asia but still has some routes. No Australian flights from the mainland, but there may be some on Continental Micronesia from Guam. I'm not sure.
Continental Domestic: Strong in Texas and in the Mid-Atlantic. Does well on transcontinental routes and east coast flights to Florida due to Newark hub.
-----------Weak in western U.S.
US Airways International: Basically just Europe, Caribbean, and Mexico. Europe served from Philadelphia. Caribbean served from Charlotte. Mexico served from Phoenix.
-----------Absent from Asia and Australia. Only of the "six majors" to have no Asian flights whatsoever.
US Airways Domestic: Both coasts. Serves West through Phoenix and Las Vegas. Serves East through Philadelphia and Charlotte. Particularly strong on East Coast due to supplementary hubs and focus cities at Pittsburgh, Washington-National, New York-La Guardia, and Boston.
-----------Weak in middle of country, especially for north-south routes.
Partnerships play key roles for each airline.
American: Serves Australia with Qantas partnership. Serves intra-Asia with JAL and intra-Europe primarily with British Airways. Serves Pacific Northwest with Alaska Airlines partnership.
United: Serves Europe with Lufthansa and others. Most east-coast presence is with partnership with US Airways. Serves intra-Canada through Air Canada.
Delta: Serves Intra-Europe through Air France. Serves Intra-Asia through Korean. Serves central U.S. through Northwest Airlines, but only on certain routes since Delta doesn't "get along" with NW
all that much.
Northwest: Serves Intra-Europe through KLM. Serves south and east mostly through Continental, but somewhat through Delta. Serves west coast through Delta at Salt Lake City.
Continental: Serves central U.S. and some of the west through Northwest Airlines. Serves Asia through Northwest.
US Airways: Serves central U.S. and Asia through United. Serves intra-Europe through Lufthansa.
The most important of these alliances are, in no particular order, probably US Airways/United, United/Air Canada, Northwest/KLM, Delta/Air France, Continental/Northwest, American/Alaska, American/Qantas, United/Lufthansa, and American/British Airways.