The bottom line first: the American electric grid begins with a number, 4 September 1882, the day Pearl Street Station in Lower Manhattan started operating and became the first central power plant in the United States. Built by the Edison Illuminating Company, the plant is described by National Grid as the first purpose-built power station, and both the Institute for Energy Research and Iowa State University credit it as the first of its kind anywhere. Its opening-day load was modest by any modern measure: roughly 400 incandescent light bulbs served to an initial customer base of about 85, residences and businesses included.
By the numbers, though, the bet was anything but small. Edison picked the site the way a retailer picks a corner lot, after extensive market research into a densely populated area mixing commercial and residential uses. The service territory, called the First District, was a rectangle with Wall Street as its southern edge, Nassau Street on the west, the East River on the east, and Spruce Street plus the former Ferry Street to the north. Among the earliest accounts were the offices of J.P. Morgan and the New York Times, and Edison, a fluent student of newspaper publicity, knew exactly what early coverage would do for present and potential financial backers. The engineering matched the site work: coal-fired steam engines generating power distributed through buried cables to nearby buildings. Customers more than quintupled to over 500 within two years. The station later burned down, but one of its dynamos survived and now sits in Dearborn, Michigan; its ancestor, the 1879 “Long-legged Mary-ann” generator, had been improved upon before more efficient designs went into service downtown.
The figure that matters most in this history is 125. That is how many years after Pearl Street that direct current kept flowing to residential and commercial customers in New York, until 14 November 2007, when the last DC section of the city finally went dark and was switched over to AC. The long overlap was messy in the way only legacy systems can be: many residences carried both DC and AC outlets that looked identical, and plenty of appliances met their end in the wrong socket, while other parts of the country had gone all-in on alternating current decades earlier.
The subway kept the DC flag flying, and still does. The system, one of the world’s largest, moves over 1.7 billion riders a year across 468 stations, with the underground lines dating to 1904 and the elevated rail to 1867. Edison himself patented a third-rail supply system for rail cars in 1882; the cars run on 600 volts of direct current to this day, drawing alternating current through oil-filled cables to substations for conversion, once via synchronous converters and mercury arc rectifiers, the last of which were retired in the 1990s after almost a century of service. For most of the 20th century three stations supplied the subway with 25 Hz AC, stepping 11,000 volts down to 400 volts before conversion to the trains’ 600 volts DC. Even the infrastructure is oversized by instinct: a Brooklyn tunnel 15.5 ft wide carries three rails.
The wider map of firsts spread quickly after Pearl Street. Great Barrington hosted the first AC distribution network built on transformers in 1886, Redlands Mill Creek 1 in California followed in 1893, Mechanicville, New York in 1897, and Schaghticoke hosted Steinmetz’s monocyclic power experiment along the way. Investors will note the pattern: the standard was settled early, the war of the currents went to AC almost everywhere, and yet the losing technology held a corner of the market for 125 years. Grid history is less a clean rollout than a very long tail.
