President Biden will formally apologize on Friday for the country's role in forcing Indigenous children for over 150 years into boarding schools, where many were physically, emotionally, and sexually abused, and more than 950 died. "I'm doing something I should have done a long time ago: To make a formal apology to the Indian nations for the way we treated their children for so many years," Biden said Thursday as he left the White House for Arizona, per the . Interior Secretary Deb Haaland launched an investigation into the boarding school system shortly after she became the first Native American to lead the agency, and she will join Biden during his first diplomatic visit to a tribal nation as president as he delivers a speech Friday at the Gila River Indian Community outside Phoenix.

"I would never have guessed in a million years that something like this would happen," says Haaland, a member of the Pueblo of Laguna in New Mexico. "It will be one of the high points of my entire life," she said of the apology. "It's a big deal to me.

I'm sure it will be a big deal to all of Indian Country." The investigation she launched found that at least 18,000 children, some as young as 4, were taken from their parents and forced to attend schools that sought to assimilate them into white society while federal and state authorities sought to dispossess tribal nations of their land. The investigation documented 973 deaths, while acknowledging the figure is likely higher, and 74 gravesites .