Tanggal sampun kapilih olih Fédérasi Wasa Karya Amérika antuk ngalanturang kampanye sadurungné indik makarya kutus jam arahina ring Amérika Serikat, sané ngamuncuk ring Paindikan Haymarket, ring Chicago tanggal 4 Méi 1886.
The date was chosen by the American Federation of Labour to continue an earlier campaign for the eight-hour day in the United States, which had culminated in the Haymarket affair, which occurred in Chicago on the 4th of May 1886.