I think csx runs an export terminal at Baltimore. NS used to and probably still does, runs a major export facility at Norfolk.
There are a bunch of coal plants on, and off the CSX A-line, also some co-generation plants that get unit trains. The Richmond Wheelwright plant used to average 150 coal cars a day (that's 150 loads in & another 150 empties out.)
Weldon, NC, Franklin, VA and Rocky Mount, NC all have co-generation plants ( I think Franklin has a co-generation plant, I know they coal trains there.).
Wilmington, NC has at least one coal burning power plant and they do some export, I think, at Leland (outside of Wilmington on the Cape Fear). Lumberton, NC has a plant, too.
There are several plants down in SC and Florida.
It wouldn't surprise me if 25% of the trains that ran down the A-line were either coal or grain. (Somewhere there's a real big hole in the ground and there's a big corn field, too).