Originally Posted by
Squeezebox
I believe that most if not all of the rail-to-trails have guidebooks. Look at their websites.
Personally I'm looking forward to moving up to GPS.
They do, but they vary in quality from Google Maps screenshots to amazing, plus just the pain of figuring out each individual trail and going and hunting them down.
Can't speak to all states, but I know the Michigan DOT produces bicycle specific maps, free for download or you can order them on the website:
MDOT - MDOT Road and Trail Bicycling Maps. Also, you may try the local state bicycling association. Again, can't speak to all states, but ours provides some good resources:
Michigan Bicycle Routes and Maps