MBTA Red Line's 100th anniversary
Extending farther northwest?
Probably not. There was a plan in the 1940s to extend the Red Line all the way to Route 128.
Strong suburban opposition killed the idea, but a tunnel still was constructed from Alewife to Arlington, and is used today for storage.
The path that would have been used for the subway was eventually turned into the Minuteman Commuter Bike Path.