May Day, also known as International Worker’s Day, commemorates the 1886 Haymarket Riots in Chicago and is often celebrated by anarchists, socialists and labor organizations alike.
The posters below come from Russia, Cuba, Palestine, Mexico, Turkey and the United States and span from 1894 to current day.
Source. This poster dates somewhere between 1920-1940 and was displayed as part of an exhibit on Russian constructivist art.