As other said, the left most lane is not the fast lane. It's for passing. Of course, if you're passing the rest of traffic, you'll be in the left lane most of the time. However, keep an eye on your rear view mirror and move right if there's someone close behind and/or flashing their high beams.

As a practical matter, the left lane in MA is 80mph+ and if you've only been driving for a year, you're not ready for that unless you've had something beyond the usual dogshit driver's ed.