There really ought to be direct no transfer rail service between Harrisburg and points south, like Baltimore and DC. I've done this trip a couple times on Amtrak and it is annoying to have to go east to then go south. Greyhound is direct, however it can be a psych ward (and germ factory) on wheels. And as we all know by now, I really have no interest in driving and the fact that cheap gas is gone forever proves I made the correct decision, even if everyone looks at me like I'm some sort of alien life form from the planet Romulus. Well hey guess what, they have flying cars on Romulus that run on magic and drive themselves and it's all free! Ha! Anyway, I digress.
A basic primer about the rail network south of Harrisburg. It's all freight rail now. As late as the late 1970s, there was passenger rail service between Harrisburg and Baltimore that ran along the tracks now owned by Norfolk Southern that run on the east side of the Susquehanna River to Port Deposit, MD, but way back in the day, one could get on an interurban (what we would now call "light rail" or if you're an ornery Philadelphian like I am, "trolleys") and go pretty much anywhere. Indeed, it was actually possible for someone to take the interurban from Lancaster all the way to Scranton, and then connect to go to New York City. While I won't expound upon conspiracies involving General Motors, the automobile was essential in killing this form of public transportation. There are almost no interurbans left, but a great example of one is just 2 hours east of here in the Philadelphia suburbs between Upper Darby and Norristown (Septa's Route 100).
Passenger rail (not interurban) service also existed, along the Northern Central Railway and the Maryland and Pennsylvania (Ma and Pa) Railway. Passenger service on the latter ended in the '50s. Most of the Northern Central's right of way is a rail trail, save a section that is currently in use as part of Baltimore's light rail system. A deep google search found a reference that Amtrak also had some service as late as the late 70s, but it, like most of Amtrak, could not make a profit. It went. It was also not that direct, and slow. Scenic, but slow.
As for passenger train service, Agnes was a major culprit by causing major damage to rail infrastructure up and down the Susquehanna Valley, the complete collapse of the private passenger rail service industry in the late 1960s and 70s (which bought us Amtrak) was another, and all of us who preferred to drive pretty much ended it.
I think it's time it came back. This link is an interesting thread to read. There is a 7 year old PennDOT report on the state's passenger rail needs. It's a PDF and an interesting read. But it's 7 years old. Times have changed. It should be updated and I think I may bring it up at work sometime soon since I don't nearly have enough things that challenge me to do (I have lots of stuff to do, it's just not challenging.)
This is something I'll be expanding on a lot more as time goes on but I drew this very basic map a couple weeks ago. I may be coming into a copy of ArcGIS that I can do a real nice fancy map on it.
View Larger Map
Ignore the pushpins. They were there to aid me in drawing the very rough lines.
The blue squiggle on the right, that hugs the east bank of the Susquehanna roughly follows existing Norfolk Southern trackage. It was the trackage that was used by Amtrak as late as the late 70s (and was apparently electrified, like the Keystone line.) As far as I know (I don't have PennDOT's freight rail network map here at home) it is the only track that exists between Harrisburg to connect in Maryland with the Northeast Corridor lines. The other lines roughly follow existing track that is freight rail (the stop in York has several at-grade crossings, if you've been to the new stadium or used the Greyhound stop there you've seen them) and the trackage generally has degraded or been ripped up for rail trails south of York and in Maryland.
This is of course just an idea. I'm not yet to the point in my research where I can come up with numbers such as money and potential travel demand for analysis, and PennDOT (officially) does not have that capability to do in house (we can talk in private about unofficially). If I could hazard a guess based on the Scranton-NYC rail line that is under serious consideration I'd say this would cost Maryland and Pennsylvania somewhere north of $200 million to get built (Scranton-NYC is just shy of half a billion dollars, last time I checked.) There aren't many major population centers between Harrisburg and the Baltimore-Washington metro, however Baltimore and Washington's commuter shield grows ever wider every day, despite the price of gas. A heavy rail like like Amtrak can be used as a commuter line. The Keystone Line basically fulfills that role.
What do you think? This is a draft of an idea that I've had for a long time. This is an infrastructure connection that should exist, did exist, and with enough noise from enough organized people with their facts right, will exist again.