As to memorials...
A similar incident happened on the Boston Commons, on day in the late eighteenth century. A few Bostonians got out of hand, they were protesting tea tax. They through rocks and snowballs at a group of British soldiers, and the soldiers fired live rounds back at them. Four died. They got a memorial.
That memorial is referred to as the United States.
Lets hope we get a memorial for the Kent State four as well.
Larry