Columbus Day is held on 12 October to commemmorate the arrival of Christopher Columbus in the Americas on that day in 1492. It is known by this name mainly in the US, where it began to be held in some states over 100 years ago, but under other names it is celebrated in several Latin American countries and also Spain, where it is known as the National Fiesta. The main American countries outside the US that hold a festival on this day are Chile, Uraguay, Argentina, Mexico and Belize - in these countries it is generally called 'the festival of the race' and is seen as celebrating the expansion of the Spanish language and culture to the New World.
Canada does not officially hold this day, but the Canadian Thanksgiving occurs around the same time.
Not all US states give this as a public holiday, as there is some controversy around the idea of celebrating an event that led to colonialism and all the suffering that came with it.