Why are American Indians sometimes referred to as Native Americans?

When referring to American Indians or Alaska Natives, it is appropriate to use the terms American Indians and Alaska Natives. These terms denote the cultural distinction between the indigenous people of the continental United States and those of Alaska. While the term “Native Americans” came into usage in the 1960s out of respect for American Indians and Alaska Natives, usage of the term has expanded to include all Native people of the United States and its territories, including Native Hawaiians and American Samoans.