1989 – The Tank Man halts the progress of a column of advancing tanks for over half an hour after the Tiananmen Square protests of 1989.

1981 – The Morbidity and Mortality Weekly Report of the Centers for Disease Control and Prevention reports that five people in Los Angeles, California, have a rare form of pneumonia seen only in patients with weakened immune systems, in what turns out to be the first recognized cases of AIDS.

1989 – The Tiananmen Square protests are suppressed in Beijing by the People's Liberation Army, with between 241 and 10,000 dead (an unofficial estimate).

1975 – The Governor of California Jerry Brown signs the California Agricultural Labor Relations Act into law, the first law in the United States giving farmworkers collective bargaining rights.

1939 – The Holocaust: The MS St. Louis, a ship carrying 963 German Jewish refugees, is denied permission to land in Florida, in the United States, after already being turned away from Cuba. Forced to return to Europe, more than 200 of its passengers later die in Nazi concentration camps.

I guess someone missed this or thought that it is unimportant ...
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1844 – The last pair of great auks is killed.

1495 – A monk, John Cor, records the first known batch of Scotch whisky.

1921 – The Tulsa race massacre kills at least 39, but other estimates of black fatalities vary from 55 to about 300.

1977 – Star Wars (retroactively titled Star Wars: Episode IV – A New Hope) is released in theaters.

1964 – Discovery of the cosmic microwave background radiation by Robert Woodrow Wilson and Arno Penzias.

1974 – Nuclear weapons testing: Under project Smiling Buddha, India successfully detonates its first nuclear weapon becoming the sixth nation to do so.

1970 – The Beatles release their 12th and final studio album Let It Be.

1998 – Steve Jobs of Apple Inc. unveils the first iMac.

Warlocks play first gig at Magoos Pizza, Menlo Park, Ca 1965

1904 – Pitching against the Philadelphia Athletics at the Huntington Avenue Grounds, Cy Young of the Boston Americans throws the first perfect game in the modern era of baseball.

1956 – The polio vaccine developed by Jonas Salk is made available to the public.

1973 – The Dark Side of the Moon by Pink Floyd, recorded in Abbey Road Studios goes to number one on the US Billboard chart, beginning a record-breaking 741-week chart run.

1981 – Xerox PARC introduces the computer mouse.