Most of the things in those (and nearly all boxes) are things we Citizens should know.
Very, very little should actually be classified; *only* the precise capabilities of the newest high-end weapon systems, communication techniques, and the identities of active spies.
I say let the fedgov have *one* box of stuff to keep secret per year, automatically becoming public information after 10 years.
It should be harder to classify *anything* than to get a building permit in a wetland.
Other things that require secrecy:
1. details of methods of finding terrorist leaders and terrorist attack plans
2. algorithms of weapons such as air-to-air missiles
3. attack plans for say Ukraine and for Iranian nuclear-related sites
4. electronic warfare technical plans
5. remaining uranium enrichment secrets
6. remaining nuclear bomb secrets
7. some emergency basing arrangements
8. some foreign country industrial plant information
9. some sourcing information for western weapons systems
10. some biological warfare technology
11. advanced tank armor
12. domestic nuclear material sensor locations
13. suspected and known terrorists and their locations