MAY DAY (International Labor Day): Postal inspectors intercept several bombs, in the mails addressed to several important Federal officials, including A. Mitchell Palmer, attorney general of the United states.

       [added 6/19/2022]

Subsequent Events:

6/2/1919                   10/7/1940                  8/6/2001

References:

Palmer Raids – Wikipedia, the free encyclopedia
en.wikipedia.org/wiki/Palmer_raids

Current U.s. National Debt:

$36,167,124,467,492

Source