We mustn't forget the events of the past (this one is approaching 100 years ago), and must never repeat them. Thank God we've gotten better.
Here are some other horrors that also don't get much coverage:
1837 - Lovejoy - torch-carrying mob murdered him for being an abolitionist https://youtu.be/Clu4lD7A1t8
1857 - Mormons murdered non-Mormons https://en.wikipedia.org/wiki/Mountain_Meadows_Massacre
1863 - Draft Riots https://youtu.be/1bxnUh86RB8
1866 - New Orleans massacre https://en.wikipedia.org/wiki/New_Orleans_massacre_of_1866
1871 - LA Chinese Massacre https://youtu.be/nauaIbOXaYo
1885 - https://en.wikipedia.org/wiki/Rock_Springs_massacre
1886 - https://en.wikipedia.org/wiki/Haymarket_affair
1919 - Red Summer (anti-black violence) https://youtu.be/Hy3a6PvIcxI
1923 - Rosewood massacre (anti-black violence and dispossession) https://en.wikipedia.org/wiki/Rosewood_massacre
1925 - ~40,000 KKK members march in Washington, DC
1932 - Bonus Army - see: . Hoover ordered Patton and MacArthur to throw out destitute veterans, women and children from peacefully protesting in DC to get their promised war pay earlier. They charged them by force. It was more benign that a veterans's Occupy Wall St. Two veterans were shot to death, a boy was killed and a pregnant woman miscarried after the police stormed a hospital with tear gas. https://en.wikipedia.org/wiki/Bonus_Army
1930's - Murphy Ranch / Silver Shirts - Nazis prepared to takeover America and round up the Jews
0. The Untold History of the United States by Oliver Stone
EDIT: Here is a first-hand account of the conditions the Spanish empire brought to the Americas.