These are the maps of Arizona counties along the National Old Trails Road from Apache County west to Mohave County. Some counties have more than one map.
The files are rather large, and may take a while to load. You can also just right-click the link and download them.
Apache County 1918 (http://www.americanroads.us/forum_files/Apache_County_1918_north_white.jpg) (north sheet)
Navajo County 1918, detail (http://www.americanroads.us/forum_files/Navajo_County_1918_north_detail_white_crop.jpg) (north sheet: whole map (http://www.americanroads.us/forum_files/Navajo_County_1918_north_white.jpg))
Coconino County 1921, detail (http://www.americanroads.us/forum_files/Coconino_County_detail_1921_crop.jpg) (whole map (http://www.americanroads.us/forum_files/Coconino_County_1921.jpg))
Yavapai County 1920, detail (http://www.americanroads.us/forum_files/Yavapai_County_1920_detail_crop.jpg) (whole map (http://www.americanroads.us/forum_files/Yavapai_County_1920_low.jpg))
Yavapai County 1920 bond issue map of highways to be constructed, detail (http://www.americanroads.us/forum_files/Yavapai_County_1920_Highways_white_detail_crop.jpg) (whole map (http://www.americanroads.us/forum_files/Yavapai_County_1920_Highways_white_low.jpg))
Mohave County 1913 (http://www.americanroads.us/forum_files/Mohave_County_1913_low.jpg)
Mohave County 1917 (http://www.americanroads.us/forum_files/Mohave_County_1917_white_low.jpg)
Mohave County 1917 road map (http://www.americanroads.us/forum_files/Mohave_County_1917_roads_white_low.jpg) (this is the best one)