Bird's eye view of Philadelphia, 1857

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DYK Philly was the first place to implement street addresses as we know them today?

The idea of having odd numbers on one side and even on the other, all counting in the same direction, was an 18th century invention. Born of the first U.S. Census, the concept succeeded despite reluctance from City Council and plenty of classic Philadelphia stubbornness.

Add it to the pile of evidence pointing to Philly as a center of innovation. We had the first library, first computer, first hospital, first street light, first cupcake…y’all know the list goes on.

This is another example — one that impacted the layout of municipalities all over the world.

It’s widely recognized that William Penn purposely created Philadelphia as the first city with a grid street system, which then became a model for countless others. But the grid wasn’t the only local urban planning concept to be adopted worldwide.

Having a coordinated address system, including the match of property numbers to the nearest numbered blocks, was also a Philly invention.

It didn’t just pop into place fully formed. The story goes like this.

Early addresses were just super vague

Philadelphia’s address system was so vague in the 18th century that it’s surprising anyone was able to find anything, even in the two-square mile, mostly rural community that existed at the time.

In the first city directory, published in 1785, households are mostly listed by their cross streets (think “3rd and Chestnut”). Some listings were even less precise. Ben Franklin’s entry, for example, read simply “Market Street.”

Cities around the globe had already begun to recognize the need for a more organized system, Officials in London ordered the numbering of plots of land in 1678, and Paris followed shortly after.

So we tried the clockwise model

The editor of that first-ever town directory, John Macpherson, eventually decided it would be useful to copy the method being used in Paris, London and other European cities.

Under that system, house numbers started on one street corner, then went down one side to the nearest intersection, and back up the other, in clockwise fashion. The lowest number ended up directly across the street from the highest number.

Known as the “horseshoe” model, it wasn’t useful for long.

As Philadelphia grew bigger and bigger, it became an obviously inadequate way to manage the streets and allow for wayfinding.

The first town directory of Philadelphia Credit: Library of Congress

Then the census forced more order

The first person to ever oversee the United States Census came up with a better idea.

First Marshall of Pennsylvania Clement Biddle — a Philadelphian, of course — was responsible for overseeing the 1790 census. Tasked with that kind of intense record-keeping, necessity became the mother of invention, and he came up with a more uniform way to keep track of properties.

Col. Biddle is the one who thought up placing odd numbers on the north side, and even numbers  on the south. Unlike the horseshoe model, street numbers moved chronologically in the same direction, and navigating the city became much simpler. As Biddle said of his new system: In Philadelphia, a “stranger” could now find “any house whose street and number is known.”

But it didn’t fully whip Philly into shape

Even under Biddle’s new and improved numbering method, city government didn’t explicitly regulate street numbers.

That means property owners still had ultimate control over their home’s label — a flexibility that became detrimental to the entire system.

As Philadelphians tore down some structures and built others on vacant lots, properties would sometimes end up numbered in the order they were built, rather than their location from east to west.

There were houses that shared the exact same address, but stood a half-mile apart. Others had to squeeze fractions onto the end of their numbers to make a distinction.

Rumor has it there was a block of Callowhill Street that started at opposite sides with the same numbers, and counted up to meet in the middle. It was a confusing and ineffective system, most Philadelphians seemed to agree at the time.

Uniformity would require legislation…and City Council had cold feet

Yet reluctant to force residents to accept even the slightest inconvenience for the greater good — remind anyone of a modern issue? — local officials punted on solutions to the address mess. Philly councilmembers insisted they didn’t have the authority to make people renumber their properties.

Until, that is, a local newspaper publisher named Morton McMichael began vigorously advocating for change.

He wrote in the North American that street numbers were not an individual choice. Instead, he argued, they were “an indispensable part of our communitary system,” and “must be properly regulated and enforced.”

With the Consolidation Act of 1854, which extended city limits to the borders of Philadelphia County, municipal government finally took responsibility for maintaining and enforcing a common numerical system.

(McMichael, btw, went on to be elected Philly mayor about a decade later.)

Final touch: segregating numbers by block

Two years after consolidation, an inventor and councilman named John Mascher came up with another innovation.

Mascher — who was also lowkey experimenting with very early 3D technology — wanted to make it even easier for Philly residents to know where an address would be without physically walking the roadway.

His idea? Keep Biddle’s original odd/even rule, but also align the numbers with Philadelphia’s numerical blocks. That means the properties between 6th and 7th streets, for example, would fall between 600 and 700.

The update, like most change in Philadelphia, was a little controversial at the time. Some local shops defiantly used their old property numbers, in spite of the new city ordinance.

But after some time, the method prevailed, and it has since become known as the “Philadelphia System.” It’s been implemented by plenty of other cities, including Chicago, Wilmington, and countless others.

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Michaela Winberg

Michaela Winberg is a general assignment reporter at Billy Penn. She covers LGBTQ people and culture, public spaces, and transportation and mobility. She also sometimes produces radio and web features...