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.