As an international event to mark the plight of workers, May Day began in the U.S. in the 1800s but in the 200 or so years since it has spread to dozens of countries worldwide.
For the most part, it has always been a day commemorated by the political left, although at various times in modern history it has been appropriated by the far-right. During the Nazi era, Adolf Hitler made 1 May a national holiday and it was marked by fascist rallies and street demonstrations.
Given that the day has traditionally been about defending the working rights of the poor, May Day has tended to have strong anti-government sentiment in most countries. But at the same time, in Communist China today and in the USSR prior to 1989, it was a state-backed event.
Since the end of the Soviet era in Russia, May Day has become a rallying point for Russians who are nostalgic for the Communist era. In many other countries, it has brought disparate groups - mostly on the left - representing the political left, environmentalists and civil rights campaigners.
Euronews looks back at some historic May Day events in Europe and elsewhere in the world.
Thousands throng Moscow's Red Square on May 1, 1928, four years after the death of Lenin in 1924.
The Nazis appropriated May Day from the German left, and after Adolf Hitler became German Chancellor in 1933 it was marked by mass rallies in Berlin and other cities.
In the UK, May Day is celebrated on the first Monday in May. On May 3, 1936, major Clement Attlee, Labour Party leader, was one of the speakers. In 1945, Atlee would be elected prime minister.
After Fidel Castro came to power in 1959, May Day became a huge annual event for the island's new communist government.
May Day has always been a major event in Communist China. In 1967, it was marked in the first year of Mao Tse Tung's Cultural Revolution, which would last until the Chinese leader's death in 1976 and result in the deaths of up to 20 million people.
A holiday in France since 1948, in 1970 thousands of left-wing Parisian workers marched through the city bearing banners protesting against repressive labour laws.
Even after the demise of communism in Russia and eastern Europe, Marxist iconography and images of the German thinker and philosopher, Karl Marx, remain common on May Day.
During the Soviet era, May 1 was a major celebration of worker solidarity, Soviet might and the advent of spring. After the Soviet collapse, it provided an opportunity for Communists and others angry over the switch to lopsided capitalism to vent criticism.
Beyond Europe, May Day is a festival in a number of Asian nations, including Japan and the Philippines, where the labour movement today uses it to attack President Rodrigo Duterte.
In this image from May 1, 2018, protesters burn an effigy of the controversial president.