...What happened to the Freedom of Information Act ?...
As far as what happened to the FOIA, the URL below has some answers to that question.
History of FOIA
You have already received some excellent answers. I agree with all of them. If you really want to get into finding stuff, you probably owe it to yourself to use more than one receiver. Here is why. You need one, or more, to simply focus on searching. Connect that receiver to a computer and use whatever software you want to log the activity while you aren't physically present.
You then might consider one, or more, separate receivers to actually scan or monitor what you have found. Granted, not everybody wants, or can afford to, have more than one radio, but, if you can or are so inclined, that is a way to do it.
Like others posted, you will find encryption and federal activity on statewide systems. Don't let that discourage you, however.
If you really want a challenge, consider trying to document every active frequency within you listening range. Along with that, document whatever sub-audible signalling they use. For example, if your local school buses are are using 155.175 with a PL of 127.3, monitor it to verify and then keep a log of it.
The way I have done it in the past is to create banks of frequencies with Butel software and use the History Log to find the PL/DPL/NAC Code/Color Code/Etc. You will find some frequencies are unused in your area and others have multiple users, each, hopefully, with a different PL/DPL/NAC Code/Color Code/Etc. When I create these banks, I arrange them in ascending frequency order with the correct steps. Verify that you have the current, correct steps. For many years my VHF high band was in 15 kHz steps (increments). For example, it went from 155.475 to 155.490, to 155.505. Now, the steps are 7.5 kHz.
You should know, too, that not all analog frequencies have a sub-audible signal. For example, the frequencies that my local PSAP uses to tone out fire departments and patch the trunked traffic on are carrier squelch. They have no PL or DPL because sometimes those can cause false signalling.
Some radios have built in recording ability. Some software has the ability to record. I have been doing that lately with Fire Tone Out frequencies. I check ProScan, see that there has been activity and then listen to the recording function to see who the fire page out was for.