The night of December 16, 1835, was frigid, so cold that the East River froze. Yet onlookers crowded on its banks in Brooklyn that night, watching New York burn down.

As they watched, the city’s entire financial district went from the thriving center of American business to a pile of ash and rubble. The river itself even burned at one point as turpentine leaked from storehouses onto the water, chased by fire. “The whole city seemed an awful sheet of flame,” wrote George William Sheldon, a chronicler of New York’s early fires.

Now known as the Great Fire of 1835, the conflagration destroyed half a billion dollars worth of property, leveled 17 city blocks, and nearly took down a booming city. And though it’s much less famous than its counterpart in Chicago, New Yorkers can thank this blaze for the water they drink and the streets they traverse even today.

The thought of New York not being one of America’s most important cities seems laughable now, but in 1835 it had only recently gained prestige and national respect. A decade earlier, the Erie Canal had shifted the country’s balance of economic power toward New York State, which now had a direct line to wealthy Midwestern cities. New York Harbor was now America’s biggest, most important port, surpassing the combined trade of Baltimore, Boston and New Orleans. And in response, the city had boomed.

Business, financial and trade districts crowded Lower Manhattan. So did new residents: The city’s population went up over 60 percent between 1820 and 1830. Construction of wooden buildings increased exponentially, but the city’s water supply couldn’t keep up with the pace of development. Not only did New York experience a cholera epidemic spurred on by poor sanitation and the city’s stagnant water in 1832, but it lacked a professional fire department with which to fight fires.

The New York City Fire Department was run on a volunteer basis and relied on the help of men who hung around the station in the hopes they’d hear an alarm. These firefighters used hoses to suck water from the East River and Hudson River instead of accessing water within the city itself.

On the night of December 16, 1835, word spread to the volunteer firefighters that a dry-goods warehouse near Hanover Square was on fire. But the news didn’t spread quickly enough. The volunteers had spent much of the previous night fighting another fire, and they weren’t exactly raring to battle another blaze. Besides, it was well below zero when the fire broke out.

When firefighters did arrive on the scene, they faced stinging winds that prevented them from getting their hoses all the way to the East River and Hudson River. The frigid air made operating their hose trucks nearly impossible, and when the firefighters drilled into the ice over the river to get water, it froze around their hoses.

It soon became clear that the firefighters simply wouldn’t be able to fight the fire. They went into damage control mode along with neighborhood residents, who rushed into buildings to remove valuables.

In a last-ditch effort to save Lower Manhattan, firefighters attempted to destroy the fire’s fuel by blowing up some of the wooden buildings at the massive fire’s perimeter. This failed. Other buildings that served as storage for potassium nitrate, or saltpeter, a compound used as fertilizer, blew up on their own. It was not until much later in the night that firefighters and Marines managed to incinerate some of the combustible buildings at the perimeter.

Eventually, the fire reached the East River and died out, but not before firefighters from as far away as Philadelphia had headed toward the city to help, beckoned by the fire’s glow. By then it had swept through 17 city blocks and covered 13 acres. All in all, nearly 700 buildings were consumed in the fire, including a post office, the stock exchange, at least one church and the Merchant’s Exchange, a newly erected building that was a symbol of New York’s economic might.

The next morning, the New York Courier and Enquirer published a damage assessment that reads like a document from an apocalyptic vision of Manhattan. “South Street is burned down…Exchange Place is burned down…Wall Street is burned down,” the paper wrote.

“This calamity falls principally upon the heavy importing merchants; and they must unquestionably become greatly embarrassed, and many of them ruined,” wrote a stunned Samuel Swartwourt, the Port of New York’s customs collector, to Congress the next morning. His prediction was right: 23 of 26 of New York’s insurance companies folded in the aftermath of the fire, while insurers in Hartford, Connecticut, became known for their ability to make good on their policies, shifting much of the insurance business north instead.

Amazingly, only two people died in the blaze. But it irrevocably changed New York. As Lower Manhattan made plans to rebuild, city planners decided to try to impose some order on the city’s topsy-turvy lower section. They widened streets and created the grid that’s still there today.

New York learned from the firefighters’ fruitless attempts to source water to fight the fire. The city expedited plans to build an aqueduct that tapped water from the Croton River, and New Yorkers soon had access to clean drinking water that could also be used to fight fires. Soon, the fire was just a memory—but the changes it imposed on the city can still be seen today.