Originally Posted by Jrozar
Where can I find a map of all the listed trail systems I see when I'm out?
What trail systems are you specifically referring to?
Beyond the official USFS maps mentioned above that cover the states of Nevada and California US Forest Service administered lands, BLM (Bureau of Land Management) has surface recreation maps available online and at their field offices.
Unfortunately, these maps aren't free. I've got a set of around 15 BLM maps that just cover southern Nevada and the eastern edge of California along the Nevada border. The maps show all the open routes into the desert, and have local recreation/historical information for mapped locations. They also show the numerous wilderness areas that are restricted from motorized recreational use. Without these maps, you can get into the wilderness if it's not well marked on the ground, and if caught be subject to substantial fines.
For Nevada, all BLM maps are available at the same Torrey Pines address listed above.