May 5, 1862: Cinco de Mayo, marks the victory of Mexican forces over the French army at the Battle of Puebla. It is primarily a regional holiday celebrated in the Mexican state capital city of Puebla, and in other parts of Mexico. It is also celebrated in U.S. cities with a significant Mexican population.

May 10, 1994: Nelson Mandela sworn in as South Africa's 1st black president.

May 13, 1830: Republic of Ecuador is founded, with Juan Jose Flores as president.

May 14-15, 1811: Independence Day for Paraguay.

May 17, 1954: Anniversary of School Desegregation Ruling – On this day, racial segregation in public schools was unanimously ruled unconstitutional by the Supreme Court in Brown v. Board of Education of Topeka, as a violation of the Fourteenth Amendment clause guaranteeing equal protection under the law.

May 23-25: Shavuot - Beginning at sunset on May 23 and ending on the evening of May 25, this Jewish festival celebrates the giving of the Ten Commandments to Moses and the Israelites.

May 17, 1527: Pánfilo de Narváez departs Spain to explore Florida with 600 men.

May 18, 1828: Battle of Las Piedras in Paraguay. Anniversary of the end of the conflict between Uruguay and Brazil.

May 20, 1902: Cuba’s birth as an independent republic.

May 25, 1810: Independence Day for Argentina. It commemorates the establishment of an autonomous government resulting from the revolution on this day. Known in Argentina as Revolución de Mayo.

May 29, 1851: Sojourner Truth addresses 1st Black Women's Rights Convention in Akron, Ohio.

May 31, 1910: Union of South Africa declares its independence from the United Kingdom.