Doc-
The Alcan was built at the beginning of WWII and was completer in 1942.
FWIW and reference.
My uncle was a combat engineer. He spent the 1st half of the war building that road. They shipped him to Europe just in time for the Battle of the Bulge.
It was built because of the Japs keeping house in the Aleutians. We needed some way to get equipment and men to AK in case they started making a push north.