After the Airline Deregulation Act of 1978, which opened up the market to free competition, every carrier was looking for an edge to win over customers and keep them loyal. Texas International Airlines created the first frequent flyer program in 1979, and Western Air followed suit the next year. Those airlines are no longer in business, making American’s AAdvantage, introduced in 1981, the oldest frequent flyer program still in use.

Airlines began serving food onboard as early as 1919, when British airline Handley Page sold pre-packaged lunches for three shillings (around $10 today). Technical innovation eventually allowed United Airlines to install kitchens aboard their planes, giving passengers access to hot meals in the sky. The airline’s early airborne diners got to choose between fried chicken and scrambled eggs.

In May 1918, the U.S. Postal Service initiated regular air mail service, but by 1925, they were contracting the job to the earliest private airlines. Early routes paid little, and the Post Office would subsidize airline losses. By 1930, the Postmaster General began paying airlines on carrying capacity instead of actual mail moved. This drove innovation for larger and larger planes, which eventually allowed for passenger service.

British Airways Overseas Corporation (BOAC), a predecessor of British Airways, helped launch the jet age, becoming the first airline to introduce regular passenger service on a jet. On May 2, 1952, a de Havilland Comet jet took off from London to Johannesburg, South Africa, with 36 passengers. The 18-hour, 40-minute trip included stops in Rome, Beirut, Khartoum, Entebbe, and Livingston.

One of the wealthiest people in American history, Howard Hughes had a passion for planes. He purchased a majority stake in Trans World Airlines (TWA) in 1939 and later worked with aircraft manufacturer Lockheed during the creation of the Constellation, whose innovative pressurized cabin allowed much faster flights at higher altitudes. He demanded Lockheed sell TWA 35 Constellations before selling any to his rivals.

Named after 19th-century sailing vessels, Pan Am’s flying boats were used to conquer long-distance travel to hard-to-reach places. Essentially flying hotels, the luxurious clippers were designed so their massive buoyant hulls were beneath their wings. This allowed the planes to act like a large pontoon, facilitating water landings and take-offs, which was essential to opening travel to remote destinations without proper runways.

In 1913, traveling from St. Petersburg, Florida, across the bay to Tampa took two hours by steamship or up to 12 hours by rail. Enter: Pilot Tony Jannus, whose “flying boat” could make the trip in just 23 minutes. His short-lived St. Petersburg-Tampa Airboat Line cost $5 a ticket (about $100 today) and is considered the world’s first commercial airline service.

One of the earliest low-cost, no-frills carriers, Southwest declared itself the peanut airline: Fly for “peanuts,” and enjoy some peanuts during the ride. Skipping the hassle of in-flight meals meant more savings for the customer. In 2018, Southwest halted their peanut pleasantries to limit potentially deadly allergy interactions, but devotees were able to purchase the nuts from their online store.

Able to fly across the pond in about three hours, the supersonic Concorde jet was a revolutionary plane for its time. The airliner first flew in 1969, but only 14 ever entered service, and with just two airlines: Air France and British Airways, flying from New York’s Kennedy Airport to Paris and London, respectively. Citing high costs, the airlines retired the plane in 2003.

Koninklijke Luchtvaart Maatschappij, which translates to “Royal Dutch Airlines,” was founded in October 1919, making it the oldest airline still functioning today. With a long mercantile history, the Netherlands recognized early on the benefit airplanes would have reaching far-flung colonies like the Dutch East Indies (now Indonesia).