Historiography of the May Revolution
Historiographical studies of the May Revolution started in the second half of the 19th century in Argentina and have extended to modern day. All historiographical perspectives agree in considering the May Revolution as the turning point that gave birth to the modern nation of Argentina, and that the Revolution was unavoidable in 1810. The main topics of disagreement between Argentine historians are the specific weight of the diverse causes of the May Revolution, who were the leaders of it among the different involved parties, whenever there was popular support for it or not, and whenever the loyalty to the captive Spanish king Ferdinand VII was real or an elaborate masquerade to conceal pro-independence purposes.
May Day riots of 1894
May Day, or International Workers' Day was a day for remembering the workers who died during the Haymarket affair of 1886. During a General Strike in Chicago, Illinois, an unknown person threw a bomb into the crowd, prompting police to fire into the crowd, killing civilians and police alike. The same day in 1890, Raymond Lavigne called for international demonstrations to commemorate the day. In 1894 the Pullman Strike in Illinois, as well as this series of unemployed workers' riots on May Day in Cleveland, prompted U.S. President Grover Cleveland to propose a bill that would make a Labor Day a national public holiday. After the Haymarket Square riot in May, 1886, US President Grover Cleveland 
feared that commemorating Labor Day on May 1 could become an opportunity to commemorate the riots. May Day celebrations have diminished in the United States, because of the creation of Labor Day.