Environmentally, what keeps the trucking industry going?

Trains are much, much cheaper than trucks; and I think they are doing more and more of the work while the trucks pickup stuff more often at a central location and more or less deliver it to stores or other locations where it will be distributed yet again.

Still, trucks are easy. You can go from one specific building in city X directly to one specific location in city Y and even if the 2 are a couple days apart this saving the logn loading and unloading periods for the train not to mention just cutting out one more middle man,so its still cost effective.

True. A train is far more efficient than a truck in moving a pound of goods. Containers arriving by train need to be sorted and distributed to many different destinations or places. The tractor trailer truck is needed to get the goods to smaller towns or places fast.

This is my $0.02 worth.

Transportation is the link between industry and sales. Trucks can get just about anywhere. I believe trucking will continue despite the cost of fuel.

They work hand in hand to be as efficient as possible. Distribution companies are pretty damn smart when it comes to moving freight, they are in it to make money and if it were more efficient to move freight by rail they would.