No, most are diesel electric. There are a few electric passenger lines, but 99.9% of all train traffic is long distance freight.
Herp derp, yeah, you're right. I was just thinking of all the local electric passenger trains, which are powered with a third rail that brings power from what I assume are local coal plants (since I think coal is still the leading source of power in the US? Might be wrong there too)
Anyways, switch to electric from steam wasn't made for efficiency reasons so much as safety and maintenance reasons, if I remember correctly. (Steam engines were still more efficient than electric when they switched everything over, at which point steam development for trains obviously started lagging behind since no one cared)
There is very little of this in the US, compared to Europe. The distances in the US are vast and passenger trains are far less common then freight hauling, if somebody wants to take mass transportation to another city they'll take a Greyhound. So that's all dependent on petroleum too.
One thing about reaching 8-10$/gal the US is that's about the price where coal liquefaction, through the Fischer–Tropsch process starts to become cost-effective. The US has a
lot of coal, including the lignite type that is economical for coal liquefaction but less so for conventional uses for coal.
So in a sense, we might very well be fueling everything with coal sometime in the future.
Also, I'd agree that the taxes on gasoline are too low. It's taxed very little and the proceeds from that fund road and bridge infrastructure, which is in dire need of overhaul as of late.