This is the link: http://www.natgeomaps.com/trail-maps/pdf-quads.
From the link:
National Geographic has built an easy to use web interface that allows anyone to quickly find any 7.5 minute topo in the contiguous U.S.A. for downloading and printing. Each topo has been pre-processed to print on a standard home, letter size printer. These are the same topos that were printed by USGS for decades on giant bus-sized presses but are now available in multi-page PDFs that can be printed just about anywhere. They are pre-packaged using the standard 7.5 minute, 1:24,000 base but with some twists:
Page 1 is an overview map showing the topo in context
Pages 2 through 5 are the standard USGS topo cut in quarters to fit on standard printers
Hillshading has been added to each page of the PDF to help visualize the topographyIt's incredibly easy to use. Once you get to the site, click on the map of the United States and keep zooming in on the area you are interested in. You have to zoom in several times to get to the "red" pointers. Click on the "red pointer" and begin exploring.
And, yes, the link has been added to my "Data Links" page.