I live about 19 miles North of Old Hwy 66 in Chambers, Arizona. An 8-mile section of the old road is an I-40 frontage road running East from Chambers to Sanders, where it disappears for awhile. There's no way to take Hwy 66 to the West - at least as far as Petrified Forest N.P. - without trespassing on private property. I know. I've tried.

Many miles of the old road between Albuquerque and Flagstaff are either gone (I-40 was built right on top) or in such disrepair that driving on it is hazardous. The major exceptions are, of course, through those urban areas where the Mother Road was "Main Street": Albuquerque, Grants, Gallup, Holbrook, Winslow and Flag. West of Flag, one can still travel the "old road" up to Peach Springs and thru to Kingman (I've traveled this route twice). What I have not yet done is the Kingman to Oatman section, which allegedly has some of the steepest grades and switchbacks on Old 66.