I'm quite amazed since it was such a conservative area. However my high school wasn't the authoritarian hellhole I hear of others being.
1-No Pledge of Allegiance.
2-Completely open campus. No classes, you were free to leave. Just like college really.
3-Not a big deal even if you did skip class. You could do that up to two times a semester before there was any consequences besides being required to take the final. That's right, if you had no unexcused absences the final was option and wouldn't count if it lowered your grade.
4-No uniforms, lax dress code, and not really enforced.
5-Pop machines everywhere on campus.
6-No idiocy about suspending students for bringing Aspirin or Swiss Army Knives.
7-No insane authoritarian rules about only being allowed to go to your locker between certain periods or having to pay for your lunch before classes instead of at lunch like in middle school.
I'm surprised really.
OK, my high school is fairly liberal, but we do have a few conservative elitists around too (not saying that conservatives are elitists, I'm saying that our school's elitists are conservative). Anyway, my point is that 1, 4, and 7 apply to my school, and 5 did until recently.
2 and 3 are the dumbest rules I have seen in my life for a school, and pretty much back up every negative stereotype I have of the Upper Midwest.
6 Is OK, as long as you have a very nonviolent school population.
So, in summary, to answer your ?, no, your school is not liberal.