with: United Airlines (UA1537, UA1469, UA1923, UA1001), SAS Scandinavian Airlines (SK6764, SK6762), TAP Air Portugal (TP8590), Avianca (AV2002)
with: United Airlines (UA247, UA2041, UA2418, UA613, UA2304), Qantas Airways (QF3664), Delta Air Lines (DL468, DL1876)
with: United Airlines (UA240, UA2394, UA758, UA1702, UA275), Air New Zealand (NZ9530, NZ9542), Singapore Airlines (SQ1375)
with: American Airlines (AA969), United Airlines (UA1596, UA665), Delta Air Lines (DL1596, DL1578), JetBlue Airways (B6611, B61611), SAS Scandinavian Airlines (SK6830)
with: United Airlines (UA2006, UA1885, UA1257, UA748, UA743), TAP Air Portugal (TP8492, TP8490), Air New Zealand (NZ9128)
with: Alaska Airlines (AS1486, AS1480, AS1490, AS1488), United Airlines (UA2048, UA325, UA1260), Singapore Airlines (SQ1402)
with: United Airlines (UA991, UA1527, UA434), TAP Air Portugal (TP4333), JetBlue Airways (B6283), Delta Air Lines (DL2040), Gol Transportes Aéreos (G38074, G38076)
with: United Airlines (UA2201, UA460, UA632), Delta Air Lines (DL2531, DL2546, DL2757), ANA All Nippon Airways (NH7262), Alaska Airlines (AS899)
with: United Airlines (UA748, UA613, UA1070, UA230, UA910), Delta Air Lines (DL5401), Korean Air (KE6775), Asiana Airlines (OZ6446)
with: United Airlines (UA743, UA2015, UA1213, UA741, UA1953, UA765), SAS Scandinavian Airlines (SK6814), KLM (KL7205)
with: Deutsche Lufthansa (LH7794, LH7792), United Airlines (UA1857, UA1649, UA2275), Westjet (WS6780, WS6778), JetBlue Airways (B6811)
with: American Airlines (AA1803, AA293, AA1048, AA1989, AA391, AA1340), LATAM Brasil (JJ7826), LATAM Chile (LA6828)
with: Delta Air Lines (DL2504), Westjet (WS6704, WS6708), JetBlue Airways (B6675), SAS Scandinavian Airlines (SK6856), Deutsche Lufthansa (LH7708), Air Canada (AC4818), Austrian Airlines (OS7741)
with: United Airlines (UA1783, UA1983, UA1640), Delta Air Lines (DL1512), SAS Scandinavian Airlines (SK6784), JetBlue Airways (B6225), Korean Air (KE7375), Virgin Atlantic Airways (VS4893)
with: SAS Scandinavian Airlines (SK6715, SK3905), United Airlines (UA496, UA1112, UA3406), Delta Air Lines (DL214, DL2486), Korean Air (KE3534)
with: United Airlines (UA247, UA711, UA1790), SAS Scandinavian Airlines (SK6754, SK6756, SK6776), Deutsche Lufthansa (LH7748), Westjet (WS6622)
with: Korean Air (KE3546, KE3536, KE3537, KE3547), Delta Air Lines (DL1993, DL1089, DL2675), Virgin Atlantic Airways (VS4769)
with: Delta Air Lines (DL2939, DL2960), Korean Air (KE3444, KE3419), China Southern Airlines (CZ1083), Virgin Atlantic Airways (VS4408, VS4406, VS4600)
with: United Airlines (UA1992, UA4900), SAS Scandinavian Airlines (SK9700, SK6772, SK6774), American Airlines (AA4454), Delta Air Lines (DL5394), TAP Air Portugal (TP8506)
with: Air China (CA7378), Air New Zealand (NZ9726), United Airlines (UA363), Hawaiian Airlines (HA51), Korean Air (KE7846), JetBlue Airways (B65851)
History
United Airlines has its roots in the Varney Air Lines air mail service of Walter Varney. In 1926 the airline flew the first schedule airline service in the country's history.
During the September 11, 2001 terrorist attacks, two of hijacked airplanes were United Airlines aircraft. An airline industry slump, coupled with economic hardship, increasing oil prices, and higher labor costs, led to the company losing $2.14 billion in 2001.
In 2011 United merged with Continental Airlines.