Photo: Randi Silberman

Remember the opening of the movie Taxi Driver? In that iconic montage, cabbie Travis Bickle motors through the slick streets of New York City immersed in clouds of swirling steam rising from seemingly nowhere.

In the aftermath of the gigantic steam-pipe blast in midtown Manhattan last month, many have wondered what on earth such pipes are still doing under the streets of the big city. This is the Wireless Age, isn’t it, so why are conduits from the Steam Age still operating underground? Indeed, while most New Yorkers know that the city uses steam for something, they have little idea what that something is. Heating maybe? And visitors to the Big Apple are left in an even greater state of confusion. Locals have often smirked as concerned tourists, who have stopped to sniff the wisps of gas emanating from drain gratings, earnestly proclaimed to their friends, “It’s okay; it’s only steam.”

If you’re among the many who haven’t a clue what all the buried steam lines are doing down there, you’re hardly alone. Even the editors at IEEE Spectrum have been wondering. So let’s try to get to the bottom of this vaporous mystery.

First, we have to know what to properly call the technology. That would be district heating—and it has been around for a long time. The ancient Romans developed a system of steam pipes to heat their homes and baths. Later, Europeans adopted the technique. And in 1877, inspired by the efforts of modern pioneers in steam power, such as James Watt, a hydraulic engineer named Birdsill Holly created the first commercially successful district-heating system, in the town of Lockport, N.Y. His idea caught on quickly, and soon district-heating schemes began popping up across the United States. The oldest Holly system still operating is in Denver, which started up in November 1880 and has been running ever since.

Holly’s little system became the foundation for the design of a much more ambitious project to supply power to the city of New York, as proposed by Wallace C. Andrews, one of the original directors of the Standard Oil Co. By 1880, Andrews had consolidated his efforts into the New York Steam Co., which mapped out a plan that divided Manhattan into 10 heating districts, each with its own central boiler plant and steam mains. The first of these was completed the following year. During underground construction of the first pipeline, Andrews often met with Thomas Edison, who just happened to be digging an underground network of his own to deliver electricity, according to a historical account published online by Con Edison Inc.