About twenty years ago -- give or take a few -- coal truck traffic on U.S. 52 in Wayne County, W.Va., was a significant public safety concern. Overloaded trucks carrying coal from mines in southern West Virginia to docks on the lower eight miles of the Big Sandy River were involved in several accidents, plus they were so numerous that it was rare to drive a few miles on a weekday without encountering one. There were probably trucks in Kentucky supplying docks on that side of the river, but U.S. 23 is a four-lane road with more room for error.
The last few times I was on U.S. 52, there were still coal trucks but not as many. Likewise, when I've been down at the mouth of the Big Sandy, I don't see as many small boats bringing coal to the Ohio for the larger boats to pick up.
The graph explains a lot about that.