Just 22 Domestic Routes: Where American Airlines, Delta & United Compete Directly

American Airlines , Delta Air Lines , and United Airlines are known as the US Big Three. They are the three largest carriers by flights, available seat miles, and various other measures. Using OAG data to examine the trio’s network in September 2024 shows 4,300+ domestic routes. However, going through them indicates that all three airlines compete head-to-head on 22.