Daban, China: These are the final days of steam on the Jitong railway, a 567-mile line in the province of Inner Mongolia that rail experts say is the last mainline steam-powered railroad anywhere in the world. Sometime in October, perhaps just as the first snows fall, the last of these coal-fired behemoths will pull out of the yard for a final run, to be replaced by a shiny new diesel.

"These trains are the best," said Gao Hongbo, 35, as he escorted a visitor into the toasty engine room, opening flaps to reveal the red hot coals in the belly of the beast. "I don't know why they don't want to use them anymore."

In fact, Mr. Gao knew very well. Indeed, all the men in the yard knew. Along the hectic road to something called progress, there is very little time for sentimentality. Diesel trains are cheaper to operate and maintain, haul bigger loads and run at faster speeds. It is as simple as that.

"As the end approaches, I'm feeling strong feelings," Mr. Gao said. "It means an era is coming to an end, since foreign countries don't have these anymore. Now is the time for development, and we've got a lot of catching up to do, but my heart tells me these things aren't bad.