Durham, NC to Washington, DC buses and trains from $26

Or, see buses and trains from Washington, DC to Durham, NC.
Here are some trips other travelers have found on Routefriend.
$26
5h 43m
1 stop
Megabus Amtrak
$49
6h 19m
1 stop
Megabus Amtrak
$53
6h 55m
0 stops
Amtrak