It used to be where the top 16 seeds would host on campus, not sure if that's still the case.
EDIT: Some quick research says they preselect the host sites before the season, all college venues.
http://espn.go.com/espn/story/_/id/10576298/ohio-high-schools-share-ice-hockey-state-title-7-overs
This reminded me of Red River-Central in '77. How many overtimes did that go?