Thousands of unions, workers and activists worldwide on Wednesday are marking the International Workers' Day, also known as May Day. May Day first emerged as an event commemorating the labor of workers worldwide on May 1, 1886, when a group of workers in the U.S. held a massive strike for an eight-hour workday. In 1889, the International Workers Conference of Paris declared May 1 an international holiday for workers, in memory of those who partook in that strike. The day soon came to be recognized worldwide as International Workers' Day. First Workers' Day celebrations were held in 1911 in Thessaloniki in Ottoman Empire by tobacco and cotton workers, while first celebration in Istanbul was in 1912. Turkey's first official May Day celebrations were held in 1923. In 1977, Labor Day demonstrations in Istanbul's Taksim Square led to the deaths of 34 and injury of 136 in what became known as Bloody May 1. After the military coup on September 12, 1980, the holiday was suspended and celebrations banned across Turkey. After being abolished in 1981, May 1 was restored as a national holiday in 2009. Taksim square -- a traditional venue for demonstrations in Istanbul -- had remained closed to demonstrations on Labor Day between 1977 and 2010. Union activists have been barred from marching to the public square since 2013. This year, Turkish trade unions and workers are holding celebrations across the country. The Confederation of Turkish Labor Unions (TURK-IS) will organize a large May Day event in the northwestern province of Kocaeli. Two of Turkey's largest trade unions -- the Confederation of Progressive Trade Unions (DISK) and Confederation of Public Sector Trade Unions (KESK) -- will celebrate the day in a joint program in Istanbul's Bakırköy district. The HAK-IS Trade Union Confederation (HAK-IS) and Confederation of Public Servants Trade Union (MEMUR-SEN) have also announced plans to hold joint celebrations in the southeastern Sanliurfa province, while the Turkish Public Workers' Union (Turkiye KAMU-SEN) will hold an event in Samsun. According to the Ministry of Family, Labour and Social Policies, out of 13,411,983 workers make a living in Turkey as of January 2019, 1,859,038 of them are members of a union -- indicating a unionization rate of 13.8%. TURK-IS has the highest number of members, with 975,000 workers, followed by HAK-IS and DISK, with 684,144 and 171,428 members, respectively.