This beauty was built for ICC/Panana by Alco/Brooks in January 1906.  The Alaska Railroad acquired it in January 1922, but retirement date is unknown.  In the photo above, #620 is heading a southbound freight train leaving Anchorage, 1919.
Okay, I know what you are wondering.  How could the locomotive been acquired by the Alaska Railroad in 1922 and the above photo shows the locomotive in Anchorage, Alaska in 1919?   Here is Alaska Railroad historian Pat Durand's theory. "The railroad was built by the Alaska Engineering Commission that received the locomotive in 1919.  The Alaska Railroad as a legal entity, to my understanding, did not exist until 1922 and that is why you will find documents with apparently conflicting dates.   That is also why so many of the little dinky locomotives never show on the ARR roster, they were just construction equipment."

Alaska Railroad photo, Jack Klingbeil Collection