In April 1919 , authorities discovered a plot for mailing 36 bombs to prominent members of the U.S. political and economic establishment : J. P. Morgan Jr. , John D. Rockefeller , Supreme Court Justice Oliver Wendell Holmes , U.S. Attorney General Alexander Mitchell Palmer , and immigration officials . On June 2 , 1919 , in eight cities , eight bombs simultaneously exploded . One target was the Washington , D.C. , house of U.S. Attorney General Palmer , where the explosion killed the bomber , who evidence indicated was an Italian-American radical from Philadelphia , Pennsylvania . Afterwards , Palmer ordered the U.S. Justice Department to launch the Palmer Raids ( 1919 – 21 )
eight bombs simultaneously exploded
1919 United States anarchist bombings
Red Scare