FIRST-Thank you Nighthiker for that web site!
SECOND-I am an Intel gathering/disseminator fool. I have a 5 drawer file cabinet full of info gathered from states, countries, pertinent news articles, etc. (it even includes a Dublin phone book). When planning a trip, I pull all of the pertinent files and start going over them.
THIRD-as a former aerial observer, navigator, and current towboat Captain, I keep charts and maps and make notes on them (local info). Notes include highwater currents, fishing spots, fords and dry creeks that are dangerous after light, medium, or heavy rains, etc.
FOURTH-I hang onto every copy of the Mother Earth News and National Geographics (including CD's) for further info.

This is how I keep local info that can save my butt !