Investment in high speed trains would help too. In the U.S. it is not practical or feasible to travel by train outside of certain very narrow corridors.

For example, if I need to go from Virginia to Los Angeles for a conference.

Flying costs $3-600 and takes about 9 hours...5 hours 33 minutes in the air, plus ground transportation.

Driving takes 39 hours. With a single driver that is realistically a four day trip, each way. Gas for this trip costs about $260. Add in vehicle wear and you're talking about the same financial cost...and probably not much less environmental cost.

So, what about the wonderfully environmentally friendly option of taking the train. To get a sleeper room would cost me more than the flight, possibly into four figures. Or I could spend the 85-90 hours in a coach seat for about the same cost as driving.

Except that there is the time cost of spending six days in transit.

Most people can't afford that. Their boss won't approve ten days leave to go to a wedding.

So, what do we need to do?

Faster trains! Improved internet on the trains so people who are traveling for work can work in transit. (Amtrak has wi-fi, but it's not fast enough to really do anything but check email on). To give you some idea, it is about 1100 miles between these city pairs:

Detroit and Dallas

Louisville and Denver

Chicago and Houston

London, England and Rome, Italy

The first three all take about 30 hours by train.

The last city pair? About 15 hours.

Half the time. 36 hours from DC to LA would still be annoying, but it would suddenly be much faster than driving and it might actually become feasible at that point.

Fewer people would fly in the U.S. if they had the option of taking the train. If the train was fast, comfortable and convenient like it is in Europe. Amtrak has nothing on the TGV at literally every level.

Aviation can also be made more efficient, and I do believe electric planes will ultimately replace many of the small puddle jumpers. Electric motors should be able to handle short runways better than jets and even possibly turboprops because of the faster way they spin up (This is also why pickup trucks are going to be all electric real soon, as soon as people realize they are BETTER than IC at pulling something out of a ditch).

We don't have to give up flying altogether. I can't take the train from Virginia to London.

But if we had improved infrastructure we could save it for long distances or for situations like some islands where flights are a lifeline as you can't always get a boat to the dock. (I'm thinking places like the Hebrides here).