The interwar period saw the birth of many of today’s oldest airlines and the consolidation of air transport from experimental services into structured national and international networks. European governments often sponsored flag carriers—such as KLM (1919) and other national airlines—to support mail, diplomatic links, and imperial or colonial connectivity, while in the Americas companies like Avianca emerged from mergers of early mail and passenger operators. In the United States, federal airmail contracts under the Kelly Act of 1925 provided crucial subsidies; many carriers started as mail contractors and added passengers once aircraft like the Douglas DC‑3 made passenger services commercially viable on their own.
Technological advances were central to this consolidation. Multi‑engine landplanes and flying boats increased range, safety, and payload, allowing transcontinental and eventually transoceanic routes, while progressive introduction of radio, navigation aids, and weather services made schedules more reliable. By the late 1930s, aircraft such as the DC‑3 enabled airlines to profit from passenger revenue alone and supported regular services on routes linking major cities, making air travel an increasingly attractive option for business and affluent leisure travelers.
At the same time, governments moved to stabilize and regulate the sector. In the United States, the Air Commerce Act of 1926 and the Civil Aeronautics Act of 1938 created a federal framework for safety oversight, route allocation, and fare regulation through institutions like the Bureau of Air Commerce and the Civil Aeronautics Authority, later the Civil Aeronautics Board (CAB). World War II temporarily redirected capacity to military needs but delivered enormous advances in engines, airframes, and navigation, as well as a cadre of experienced aircrew and maintenance personnel, which greatly facilitated post‑war airline expansion.
Related topics
- The origins of air transport (before 1920)
- International organizations are born (1940s)
- Jet engine innovation and its consequences (1960s)
- Air transport deregulation (1970s–1990s)
- The beginning of the 21st century: from September 11 to COVID (2001–2020)
- Fighting carbon emissions: from the Paris Agreement to 2050