The hazards of citing AASHTO's 1989 route log

[usends]

I recently obtained a copy of AASHTO's 1989 US route log.  The pdf version included a table of contents page, along with a listing of mileages for each US route.  But the verbiage on the TOC expressly noted that the mileages listed there included the bannered routes associated with each mainline route:

So in other words, the mileage totals listed on that page were never intended to reflect the actual terminus-to-terminus mileage of the mainline US routes.  Yet unfortunately in the 30+ years since, that's exactly how those figures have been misconstrued by all kinds of people, from the authors of FHWA articles, to the editors of Wikipedia pages, to state DOTs that have manufactured signs like this one. 

By examining the detail pages of each US route, one can add up the state subtotals to calculate AASTHO's actual end-to-end mileages (as of 1989).  For any routes that had associated bannered routes, those end-to-end mileages will be less than the numbers listed on the TOC page.  As one example: US 1 on the TOC page was listed as 2593 miles.  But the detail page shows that figure included 216 miles worth of bannered routes, and that the total mileage for mainline US 1 was actually only 2377 miles.

(Credit goes to Mapmikey for discovering that bannered routes were included in the mileage totals, but until now I did not realize that AASHTO stated that from the outset.)