The Kent State Shootings took place on May 4, 1970. In that incident the Ohio National Guard murdered four college students during a Vietnam War protest.
Also in 1970, Larry Rivers (1923-2002) created a portfolio of screenprints called The Boston Massacre.
SOME (VISUAL) AFTERTHOUGHTS ON THE BOSTON MASSACRE
While not part of the Boston Massacre portfolio, the final screenprint, Confederate Solder, was made at the same print studio in the same year. It is the artist's own pink pastiche of his famous 1959 painting, The Last Civil War Veteran.