7/8" with back paper from Chicago maker Geraghty. While the word "Haymarket" does not appear on this button the initials "HM" do appear along with entwined letters "VA" likely standing for the words 'Veteran's Association.' While the events of the Haymarket massacre occurred over several days the term refers to the aftermath of a bombing that took place at a labor demonstration on Tuesday as dated on this button "May 4th 1886." A very historic and very rare labor related button related to the earliest years of a long struggle by striking workers to achieve an eight-hour day. NM and displays Mint. See Wilson "8 Hours" #253.