Born in Sweden, Arnoldson emigrated to the United States as a young girl and later
studied at Stanford, the University of California-Berkeley, and the University of
Montana. She never married and lived in the home her parents had built in Missoula,
Montana, near Sacajawea Park. She dressed like a man and wore jodhpurs and leather
boots. She did a lot of mountaineering, and had various lesbian lovers.