After legally completing their merger last year, US Airways and American Airlines began operations to become the world’s largest single carrier. US Airways began repainting planes in American Airlines’ livery and merging booking systems (cross-listing flights as AA and US for the carriers). Just Wednesday, the FAA issued American Airlines and US Airways a single operating certificate, letting them legally operate as a single carrier.
This is an excellent graphic showing the genealogy of the major US carriers prior to the US/AA merger. (Click the below image for a larger version.) You can see the consequence of airline deregulation around 1980 (Airline Deregulation Act passed in 1978) with regional carriers merging into larger carriers (e.g., Republic, Continental, PanAm).
