If you grew up around North Dakota, you’ve heard of the Mandan tribe, and you might even be a member. What you may not know, is that the last full-blooded Mandan was Mattie Grinnell, who lived to be 108 years old. She died on this date in 1975. She passed in Twin Buttes in the home of her daughter, Rose Fournier. Living over a century, Grinnell saw many changes in her time.