April 26, 1954 – The Salk polio vaccine field trials, involving 1.8 million children, begin at the Franklin Sherman Elementary School in McLean, Virginia. Children in the United States, Canada and Finland participated. One year later, researchers announced the vaccine was safe and effective and it quickly became a standard part of childhood immunizations.
April 28, 1789 – Three weeks into a journey from Tahiti to the West Indies, the HMS Bounty is seized in a mutiny led by Fletcher Christian. Captain William Bligh and 18 loyal supporters were set adrift in a small boat. Christian and other mutineers eventually establish a settlement on Pitcairn Island. Bligh survived and resumed his shipping trade.
April 29, 2004 – President George W. Bush dedicates the World War II Memorial in Washington, D.D. It consists of 56 pillars, representing U. S. states and territories, and a pair of small triumphal arches for the Atlantic and Pacific theaters of the war and sits on the National Mall between the Lincoln Memorial and Washington Monument.
May 1, 1960 – American U-2 spy plane pilot Francis Gary Powers was shot down over central Russia.