Amtrak's Route Performance Page

Amtrak has recently launched a Route Performance Page on amtrak.com. This page covers all nationwide routes and their historical on-time performance.  This site blames most delays on freight trains causing delays.

From the page:
We know that on-time performance is an important ingredient in fulfilling Amtrak's quest for providing quality customer service. As many of you know, the tracks Amtrak trains travel outside of the Northeast Corridor are owned by various host freight and commuter railroads. We offer this information as an opportunity for you to follow along as we work with those railroads on the path to improvement and to assist you in planning your trip.

Of particular interest to Philly-NYC Amtrak commuters are the Acela, Regional, and Keystone train on-time performance (OTP) pages.