Back in the mid-1980s, Chuck Fisk and his sons walked across Massachusetts following an old mysterious set of railroad tracks to see where they'd take them. The journey became an unpublished manuscript called "These tracks don't go anywhere." 

Click on the image to the left and you'll find the chapter that specifically deals with the MCRT--from Northampton to Boston--mile by mile. With both text and old topo maps, it is VERY accurate and a great resource for those of us reassembling the corridor today.