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On June 3, 1989, as midnight approached, the Chinese army began advancing on Tiananmen Square with tanks. The following day, June 4, saw the massacre itself. The action suppressed the student-led democracy movement that had occupied the square for weeks. The death toll remains unknown — estimates range from hundreds to thousands. The iconic "Tank Man" photograph was taken on June 5.

On June 3, 1965, American astronaut Edward White performed the first American spacewalk, spending 23 minutes outside the Gemini 4 capsule. White described the walk as the most beautiful experience of his life and had to be ordered back inside. White died two years later, on January 27, 1967, in the Apollo 1 fire during a ground rehearsal.

On June 3, 1906, in Hellgate, Montana, the first federal use of the electric chair in US history took place. The device was invented by dentist Alfred Southwick and promoted by Thomas Edison, who hoped to associate executions with the alternating current of his rival George Westinghouse, in the famous "War of Currents" of the nineteenth century.