Justin does Dallas!
Sweetwater, Texas - Travelling by train was once the American way to travel. The railroads shaped and formed this country in a much more profound way than the car ever has.
In Europe railways were built between existing towns and cities. In America the railroads brought towns and cities into being. Tracks were laid out into the great open unpopulated spaces of this country and people poured along them, seeking their fortunes.
The vast westward movement of people that was fostered by the railroads led, in 1890, to the US Census Bureau declaring that the frontier (that great symbol of America's boundless potential) had ceased to exist. There was no longer a line that marked the end of civilisation and the beginning of the wilderness.
"The United States", says John Steele Gordon in his history of the American Economy, An Empire of Wealth, "was now a continental nation in geopolitical reality as well as nominal geographic fact".
In that sense the railroads made America.
Farmers and ranchers followed the railroads out west, opening up huge tracts of new land and vastly increasing America's agricultural output. This, in turn, provided the industrial centres in the East with the cheap food they needed to keep on growing.
Gordon describes how what had been a patchwork of local markets was laced together by the railroads "into what was increasingly an economically cohesive whole".
It was the creation of a single market on a continental scale which allowed the great leap forward of American industry and finance.
In 1865 there were 30,000 miles (48,280 kilometres) of track and America was essentially an agricultural nation. By 1910, one generation later, the network covered 350,000 miles (563,270 kilometres) and the United States was the greatest and most modern industrial nation on earth.
I've been thinking about railways because, as the BBC's Ethical Man, my producer Sara has ordered me to keep my environmental impact to an absolute minimum. We have been travelling to Texas and instead of flying we took the train.
It is a long journey, two whole days. We've rattled all the way from the snowy streets of Washington to the warm Dallas spring, stopping in at a wintery Chicago along the way.
People say that the problem with travelling by train is that it takes so much longer than flying, but actually that is the great pleasure of taking the train.
We have had time to relax and meet some interesting new people. Yes, that was Daryl Hannah in the photo in the last blog. She is worried about global warming and wants to reduce her impact on the environment. It was our good luck that she just happened to be on the same train as us.
Travelling by train gave me the time to read Gordon's book and as I read it struck me that the transformation of American society brought about by the railroads isn't that different in scale from the technological revolution that is needed to transform America and the world to a low carbon economy.
The scientific consensus is clear. We in developed nations need to cut carbon emissions by at least 80% by 2050. But, since the world really began to wake up to the dangers of global warming a decade ago carbon emissions have not fallen, they have risen. It does not encourage confidence in our ability as a species to deal with the problem.
In my last blog I discussed how the change in policy here in America has dramatically increased the chances of a global agreement to cut emissions.
But even if an agreement is reached some people argue that there is not enough time for our societies to make the profound and fundamental transformations needed to move to a low carbon economy.
But there is reason for optimism. We have come to Texas, the oil capital of America and the most polluting state in the Union, because an energy revolution has already begun here.
We have come to West Texas, what was once the great American frontier. This was Comanche territory. The vast open plains stretch from horizon to horizon and only buffalo hunters and a few intrepid ranchers would ever venture here. Until, that is, the railroads came.
The mighty Texas and Pacific Railroad pushed through West Texas in 1881 and along the way gave birth to the town of Sweetwater.
Sweetwater was a pretty wild place then. Saloons and bordellos lined the streets, serving the cowboys and later the oil men.
But the glory days of Sweetwater came to an end years ago, and the town went into a long, slow, decline. When the oil price collapsed in the mid-Eighties it looked like Sweetwater and the towns around it might actually shut down completely.
The Mayor of Sweetwater, Greg Wortham, described to me the terrible drought that almost bankrupted the last few ranching families here. Many had sold their cattle, their children had moved away and they were just about ready to call it a day.
Then, just a couple of years ago, Sweetwater discovered it was on the boundary of a new frontier, a new energy frontier.
In a decade the prospects of the town have been reversed. Billions of dollars have been invested here to create an energy industry that leads the world. The boom times are back for Sweetwater, but not the bordellos or saloons, this is strictly a clean energy revolution.
I've got to go out and take a look at what has been happening in Sweetwater now but I will write more about the energy revolution here in the next blog. Click on the funny orange "feed" button in the left hand column and the BBC will tell you when it is posted up.
In the meantime tell me if you think I am right about the scale of the transformation that is needed and whether you think my comparison with the railroads a good one.
Please comment now.