Did U.S. plains indians not have facial hair or did they shave? I don't recall seeing facial hair on early photographs, drawings, paintings, etc.

Nope. They just don't. It doesn't grow for some odd reason. My friend's grandfather hasn't shaved a day in his life.

Thanks for your answer!

The Native American's or Indians of North America have in their original make up low levels of body hair. The easter woodland Native Americans used clam shells to pluck out stray hair growing on the body. Plains Natives also if need plucked or pulled out any unwanted body hair.

Some Native American's have facial hair and some do not. I see Native Americans where I live and work and some have mustaches and goatees. Generally speaking, Native Americans do not grow facial hair as quickly as those from Europe or even Africa.

I found this article for you -
Native American Philosophy