"May Day"@en . "International Workers' Day, also known as Labour Day in some places, is a celebration of laborers and the working classes that is promoted by the international labor movement, anarchists, socialists, and communists and occurs every year on May Day, 1 May, an ancient European spring holiday. The date was chosen for International Workers' Day by the Second International to commemorate the Haymarket affair, which occurred in Chicago on 4 May 1886."@en . . . . . . "International Workers' Day"@en . .