While most people know Monday as Columbus Day, some states celebrate an alternative to the holiday with Indigenous People’s Day. While the two holidays fall on the same day, they celebrate very different ideas.

Indigenous People’s Day is a celebration of the contributions of Native Americans as well as their history, History.com said. Columbus Day, on the other hand, celebrates the discovery of the Americas by Italian explorer Christopher Columbus in 1492.

The change from Columbus Day to Indigenous People’s Day occurred after activists, who say that Columbus enslaved Native Americans, said the explorer should not be credited with discovering the Americas, when Native Americans already inhabited the land. (Also, Leif Erikson explored North America before Columbus.)

This has led to activists calling for the removal of Columbus statutes and monuments, saying they are a symbol of slavery.

Several states celebrate Indigenous People’s Day alongside Columbus Day and have done so since 1991. This includes the states of Alabama, Alaska, Hawaii, Idaho, Maine, Michigan, Minnesota, New Mexico, North Carolina, Oklahoma, Oregon, South Dakota, Vermont, and Wisconsin.

More than 130 cities also recognize Indigenous People’s Day, including Seattle, San Antonio, and Washington, D.C., instead of Columbus Day or in addition to the holiday.

native americans Phil Little Thunder from the Rosebud Reservation wears his ceremonial outfit in the tribal area on the grounds of the Fort Laramie National Historic Site in Fort Laramie, Wyoming, April 29, 2018. Photo: REUTERS/Stephanie Keith