Back in the day, the line did run all the way to West Chester. I once did a joyride on it when I was in high school, and then rode back on what is now the 104 bus (which years ago was a Red Arrow Trolley) back to 69th St. Terminal. I'm not sure why they cut it back, and, if AmtrakMaineiac in
post #6 is correct, the folks in Chester County might be satisfied with the service on the Maine Line to Exton and Thorndale and don't feel the need to pay for extending the line to West Chester. I recently drove through that area, the sprawl is pretty horrific, and driving to Exton/Thorndale is probably just as good to the average traveler taking a train to Philly as driving into downtown West Chester, and there's probably more parking at Exton and Thorndale than downtown West Chester. However, at some point, there might be interest in turning downtown West Chester into a walkable mixed-use urban center, and then having a train station in the middle of town might be seen as having a higher priority for public spending. But who knows when, or if, that will ever happen.