Even as superhighways supplant older surface routes, some historical highways get attention from those with antiquarian (and commercial) interests in the continued recognition of such routes. US 66 in the midwestern and southwestern United States is a prime example of such efforts; "Historic Route US 66" markers, completely unofficial, designate most of the old surface road, some of which has literary significance (as in John Steinbeck's novel The Grapes of Wrath).
