On this day in 1927, the first cooked meals on a scheduled flight were introduced on an Imperial Airways flight from London to Paris.
On this day in 1931, the Empire State Building was dedicated in New York City.
On this day in 1956, the polio vaccine developed by Jonas Salk was made available to the public.
And on this day in 2011, US President Barack Obama announced that Osama bin Laden, the suspected mastermind behind the September 11 attacks had been killed by US special forces in Pakistan. Due to the time difference between the United States and Pakistan, bin Laden was actually killed on May 2.