Columbus Day is observed in the US the second Monday in October unless you live in one of these four states.

This year, the federal holiday is celebrated on October 13 except in Alaska, Hawaii, Oregon and South Dakota.

The first state to officially observe Columbus Day as a state holiday was Colorado in 1906. It became a federal holiday in 1937. The date was fixed as the second Monday in October in 1970.

Two states that don't observe Columbus Day, Hawaii and South Dakota, observe the day with their own holidays. In Hawaii, the day is celebrated as 'Discoverer's Day' to commemorate the Polynesian discovers of the islands. South Dakota observes the day as an official state holiday called 'Native American Day'.

[Wikipedia]