according to the chronicle the average assistant professor salary is ~$80k. I doubt that a native american studies assistant professor will get that much but I have been wrong before.
That averages the science and engineering professors with the liberal arts professors. At my school, I know the starting salary for a CS professor is going to be around $85k. But looking at the History department, I see some assistant professors as low as $52k.
See: http://www.collegiatetimes.com/databases/salaries/salary?nam...