Delta Air Lines is the oldest airline from the United States still in operation. Delta was founded in 1925 as the world's first aerial crop dusting operation called Huff Daland Dusters, Inc. Huff Daland quickly acquired more 18 planes and became the world's largest privately-owned fleet at the time.

As of 2026, American Airlines is the oldest U.S. airline still operating under its original lineage, having celebrated its Centennial (100th Anniversary) on April 15, 2026. The airline traces its roots back to 1926 when Charles Lindbergh flew the first bag of mail for Robertson Aircraft Corporation, one of the many smaller carriers that eventually merged to form American Airways (later American Airlines). To celebrate its 100th year in 2026, the airline has introduced a commemorative "Forever Forward" livery on select Boeing 787s and opened a historical exhibit at the CR Smith Museum in Fort Worth. While Delta Air Lines also has roots dating back to 1924 (as Huff Daland Dusters), it did not start scheduled passenger service until 1929, giving American the edge in continuous operational history. This milestone reinforces American Airlines' position as a "legacy" carrier that has survived the transition from the "Golden Age" of props to the modern era of ultra-efficient, carbon-neutral-focused jet travel.