Indigenous Peoples' Day is a holiday that celebrates and honors Native American peoples and commemorates their histories and cultures. It is celebrated across the United States on the second Monday in October, and is an official city and state holiday in various localities. It began as a counter-celebration held on the same day as the U.S. federal holiday of Columbus Day, which honors Italian explorer Christopher Columbus. Many reject celebrating him, saying that he represents "the violent history of the colonization in the Western Hemisphere". Many activists believe that this holiday is a sanitation or covering-up of Christopher Columbus' actions such as enslaving Native Americans. Indigenous Peoples' Day began in 1989 in South Dakota, where Lynn Hart and Governor George T. Mickelson backed a resolution to celebrate Native American day on the second Monday of October, marking the beginning of the year of reconciliation in 1990. It was instituted in Berkeley, California, in 1992, to coincide with the 500th anniversary of the arrival of Christopher Columbus in the Americas. Two years later, Santa Cruz, California, instituted the holiday, and in the 2010s, various other cities and states took it up. It is similar to Native American Day, observed in September in California and Tennessee.