Inside first transcontinental railroad tunnel
In the 1860s, America built the first transcontinental railroad across the country and many of the labourers who cut the tunnels by hand for a pittance in wages were Chinese.
Today, President Obama has made high-speed rail a priority, with the first line planned for California.
The Chinese are again involved, but this time proposing to design it, build it and part-fund it.
Quite a turnaround, which says a great deal about the changing world order.
Alastair Leithead visits one of the sites on the route of the original transcontinental railroad, in the Sierra Nevada mountains in California.
24 Jun 2011