In 1927, Pan American Airlines completed its first flight, from Key West, Florida to Havana, Cuba. Ironically, the first flight was over water and the airline would pioneer numerous oversea flights. The company began by flying air mail between the United States and South America, using Martin 130 and Boeing 314 flying boats. Pan Am Airlines was contracted with United States military forces during World War II, which benefited the company greatly. The airline flew more than 90 million miles on behalf of the war effort, and its pilots gained much experience. Following the war, the military aircraft were converted into passenger airliners to capitalize on a huge growth in passenger travel. When the need arose for longer mail flights in the late '60s and early '70s, the company needed new planes. Pan Am called upon Boeing for 707-320Cs, DC8-30s, and later, 727-100s. Those planes carried air mail throughout the world. When the federal government began to look into monopolies, Pan Am took some of the worst hits and was forced to relinquish some of their routes to other airlines — at the same time that passenger air travel numbers began to take a dive. Pan Am eventually went under in December 1991 and Delta acquired the airline, continuing to fly its planes under the famous name for a short time, then slowly converting all the planes to bear the Delta logo.