Free USGS Topo Maps
In the 1940’s the U.S. Geological Survey began surveying the entire contiguous U.S to create a series of topographical maps. The USGS topo maps are considered by many to be the most accurate maps available and are used by paddlers, hikers, climbers, and cyclists alike for outdoor recreation. 
These maps are now available for free in the public domain for download or home printing from the USGS website. Simply go to http://store.usgs.gov and click on the “Download Topo Maps Free” link on the right. Use the Google map interface to locate the area you would like a map of. Once zoomed in click on the Red “Mark Point” and download the map you want.
When I went to the map locater page I found it nearly impossible to find maps using the zoom feature. The search function to the right of the Map Locater proved much easier. Simply type in the name of a park, mountain peak, landmark ect. and you will be taken to the individual “Mark Point” where you can download the map in question.