Interstate 90 by FlaxmanR

Question 5

A sign on westbound I-90 in the town of Becket, Massachusetts states that the next highest elevation on I-90 is in Oacoma, South Dakota. That’s not actually true, as pointed out in a 2014 Slate piece, but it’s still a fun highway sign. This sign, at a mere 1,724 feet of elevation, is located within what subrange of the Appalachian Mountains that runs across western Massachusetts?