International Workers’ Day, also known as Labour Day in some places, is a celebration of labourers and the working classes that is promoted by the international labour 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. This day has its origins in the labour union movement, specifically the eight-hour day movement, which advocated eight hours for work, eight hours for recreation, and eight hours for rest.
Being a traditional European spring celebration, May Day is a national public holiday in many countries, but in only some of those countries is it celebrated specifically as "Labour Day" or "International Workers’ Day". Some countries celebrate a Labour Day on other dates significant to them, such as the United States, which celebrates Labor Day on the first Monday of September.
Beginning in the late 19th century, as the trade union and labour movements grew, a variety of days were chosen by trade unionists as a day to celebrate labour. In the United States and Canada, a September holiday, called Labor or Labour Day, was first proposed in the 1880s. In 1882, Matthew Maguire, a machinist, first proposed a Labor Day holiday while serving as secretary of the Central Labor Union (CLU) of New York. Others argue that it was first proposed by Peter J. McGuire of the American Federation of Labor in May 1882, after witnessing the annual labour festival held in Toronto, Canada. In 1887, Oregon was the first state of the United States to make it an official public holiday. By the time it became an official federal holiday in 1894, thirty U.S. states officially celebrated Labor Day. Thus by 1887 in North America, Labor Day was an established, official holiday but in September, not on 1 May.