Commenter res calls our attention to a 2012 study [PDF] from the Stanford Center for Education Policy Analysis regarding public school teachers and principals:

Thus, black principals are relatively over-represented in the principal workforce compared to teachers. …

This result is somewhat surprising given that almost all principals are former teachers. …

Black teachers have the highest probability of becoming principals throughout the teacher lifecycle. Hispanic teachers have the lowest probabilities and the probabilities for white teachers are situated between the two minority groups. The racial differences in the hazard functions are statistically significant.

The inclusion of teacher characteristics, school characteristics, and year fixed effects increases the odds ratio from 2.18 to 6.36.