What degree do you need to become a college professor for sociology or history?

Answer 1

To become a college INSTRUCTOR, you only need a Master's degree in the field [or relevant experience, in some cases].
To become a college sociology or history PROFESSOR you will need a PHD in socilogy or history or a related field.

Answer 2

Depends on what level you would like to teach. If you'd like to teach at the community college level, then probably a Master's degree suffices. But to teach at a university, you would need a PhD.