— People Express. One of the first airlines to take advantage of deregulation. People Express was modeled after a British low-fare airline, and started flying in 1981 in Newark, N.J. It grew quickly — maybe too quickly. Burdened with debt, it was merged with Continental in 1986. A new carrier began using the name last year.
— Northwest Airlines. The Minnesota-based carrier was noted for its strong routes across the Pacific to Japan. In 1993, it formed a partnership called a code-sharing agreement with Dutch carrier KLM, and that deal became the forerunner of modern airline alliances. Delta Air Lines bought Northwest in 2008, making Delta the biggest airline in the world — at least until 2010.
— Continental Airlines. It began as Varney Speed Lines in the 1930s and eventually grew to offer transcontinental and international service. Lorenzo's Texas International bought the airline and combined it with others including Frontier and New York Air. It went through two bankruptcies but was brought back from the brink by CEO Gordon Bethune. It combined with United Airlines in 2010, allowing United to surpass Delta as the world's biggest airline. The final Continental flight landed in March 2012.