The Memphis Massacre of 1866 broke out on May 1 of that year after Black Union veterans and police were involved in an altercation surrounding the arrest of a Black soldier. The ensuing skirmish spiralled out of control due to the racial tensions that followed the end of the US Civil War, lasting for two days and claiming the lives of 46 Black people and six whites.  The riot later cemented support for what would become the Fourteenth Amendment to the US Consitution, ensuring equal protection under the law. Learn more about the Memphis Massacre.  

On May 1, 1707, the two Acts of Union went into effect, implementing the Treaty of Union and thereby uniting the Kingdom of England and the Kingdom of Scotland to create the United Kingdom of Great Britain. The Union with Scotland Act was passed by the Parliament of England in 1706, and the Scottish Parliament promulgated the Union with England Act. Learn more about the Acts of Union from the Parliament of the United Kingdom.

On May 1, 1794, the Federal Society of Journeymen Cordwainers (shoemakers) was organized in Philadelphia to negotiate wages for its members, becoming the first trade union in the United States. Learn more about the history of the labor movement in the United States, and visit the website of the AFL-CIO, the federation of America's labor unions, representing more than 13 million workers.