Is McWhorter an Irish or Scottish name?

Answer 1

Yes. That is to say, it originates from Scotland AND Northern Ireland. Both places were the home of the same Gaelic people, and to complicate matters Northern Ireland was later deliberately populated with Scottish Protestants. There is a general rule that names beginning with Mac are Scottish, while those in Mc are Northern Irish; but as surnames, historically, change from one generation to another, that's no guide.

Answer 2

Scottish. Check out the McIntyre tartan.