Depends on the institution, field of study, region, as well as credentials.
A community college professor on average will start in the mid/high 40s and max out somewhere around 60-70k for a tenured full prof.
At large research universities, at the lowest end you'll have liberal arts Prof's that start around low/mid 50s and top out around 70-80k for department heads. At the highest end, you'll have business profs. Starting pay for a new Ph.D business prof is usually around low 80s to 90s; Though entry-level finance assistant profs hitting 100k+ is not unusual. Well established business profs can hit 200k+ quite easily if you count endowments (extra pay from private donors) that are very common with business professor positions.
Lecturer's, who aren't professors, are paid on a per-credit hour basis. Typically they don't make anything worthwhile and as such, most just do the job part-time.