Washington, DC to Lancaster, PA buses and trains from $37

Or, see buses and trains from Lancaster, PA to Washington, DC.
Here are some trips other travelers have found on Routefriend.
4h 42m
1 stop
Greyhound Amtrak
8h 28m
1 stop
3h 19m
1 stop
10h 48m
2 stops
VRE Amtrak
7h 30m
1 stop
GotoBus Amtrak