Buffalo in North America?

I was recently driving the back roads into Gatlinburg and noticed a field with some buffalo. My sister says that buffalo are not in the United States but I know what I saw and I have read that they are also out west. Who is right, me or her?

Actually, buffalo are not indigenous to North America. They reside mainly in Africa or Asia, with a small population also in Poland. When settlers came to this land and encountered bison they mistakenly called them buffalo because both animals share many physical characteristics. Some refer to bison as the American buffalo, so perhaps you can both be correct.