The length of the original U.S. 66 is commonly cited as 2,448 miles (although Wikipedia lists it as 2,451 miles).
Stefan Joppich’s research indicates through bypasses and improvements, the length of Route 66 dropped in miles to 2,278 by 1947 — much of it through the bypass of Santa Fe, which lopped off almost 120.
How long would it be if you traveled it now? A subscriber for the route66 group on Yahoo! did some number-crunching via Google Maps and used Jim Ross and Jerry McClanahan’s “Here It Is” maps to help modern-day travelers successfully traverse the Mother Road. The numbers were assembled into a spreadsheet.
The final answer for the length of Route 66? 2,387.5 miles.
The user, known only as xy47402 but a longtime contributor to the group, chose the “preferred” paths of the route by avoiding interstates as much as possible. The mileage obviously would vary depending on which alignment a traveler would choose.
For what it’s worth, that would put the midway point of few miles east of the Texas-New Mexico border town of Glenrio, instead of the traditional halfway point of Adrian, Texas. You can read xy47402’s notes in this eight-page PDF document here.
In an email, xy47402 said it took nearly 50 hours to do the research on Google Maps and compile the data. Some minor errors may exist, but the work provides the most definitive answer for Route 66’s total current length.
(Image of Route 66 shield in California by Randy Heinitz via Flickr)