From the Amtrak site:

Northeast Regional Business Class and Quiet Cars Located at the Rear of the Train
Effective April 11, 2016

Starting April 11, The Business class cars and Quiet Cars on Northeast Regional trains will be located in a different position than you may be accustomed to. The Business class car will be at the very rear of the train adjacent to the Quiet Car.

Amtrak Operating personnel will begin this process on April 11, and by April 14, the Business class car and Quiet car will be at the rear of all Northeast Regional trains.

This change will help Amtrak to improve operations and better serve our valued customers. For reservations and information visit Amtrak.com, use our free mobile app or call 1-800-USA-RAIL (1-800-872-7245).

Amtrak and the entire Northeast Regional team appreciate your business and looks forward to serving you in the future.

Thank you for choosing Amtrak.