In 1926, the United States created a legal precedent for zoning our cities with the decision in the Euclid v. Ambler case. This ruling was reinforced with the publication of the final Standard State Zoning Enabling Act. Zoning, for better or worse, became the primary way we think about planning cities. The most important result of this is an environment in which we plan cities primarily by locating uses (even if those uses are mixed).
Two years after Euclid v. Ambler, the Department of Commerce published another Act, the Standard City Planning Enabling Act. In this simple and clear publication, the DOC made the case that any city should be laid out, first and foremost, through the projection of streets. This enabled cities to determine what is public (streets) and what is private (blocks), and that these things are carved, or subdivided, out of a lot of land, regardless of its ownership or status.
In the 90 years since, the first publication has had far more impact on the physical landscape of the United States, and, one could argue, much of the rest of the world. The basis of the subdivision of land has been rendered subordinate to the idea of planning around the future use of a thing.
An outcome of this shift in thinking has been the idea that things must be separated. A single sentence is embedded in almost every subdivision ordinance in every jurisdiction throughout the US: ‘Local streets shall be so laid out that their use by through traffic will be discouraged.’ This quote comes specifically from the City of Atlanta’s 1957 Subdivision Ordinance. Embedded in this simple sentence is the idea that we shouldn’t be designing communities that are connected to one another.
The diagram below shows us what this simple premise results in:
If we follow a rule that discourages connectivity, it means we will never end up with anything like the great cities that were laid out and built prior to this change. Think about a city like Philadelphia (below), one of the first things done by city leaders was laying out streets, even though, as the first image clearly indicates, this was largely speculative and simply an agricultural area. This series of plans of the city clearly shows how a system of streets can provide a simple way for cities to grow, and also, thankfully, a city where people can walk. In 1957, in Atlanta, not too many people were thinking about walking.
Subdivision ordinances today are incredibly complex, tied to comprehensive plans that are silent on larger-scale issues like the physical layout of cities (let alone substantive on telling people where future streets should be located), creating places that are unwalkable, disconnected, and completely unlike the original city of Philadelphia and its counterparts. In fact, most subdivision regulations make it illegal to replicate those places like Philadelphia, Manhattan, Savannah, or Chicago that people have long appreciated for their pedestrian scale and mixed uses.
The good news? There is a very simple solution. It may be hard to imagine, but a simple, two-sentence subdivision ordinance could result in much better places and much better cities:
A ‘block’ is a portion of privately owned land that is surrounded on all sides by public rights-of-way. No block perimeter shall exceed 2400 feet.
What would the result of this be? Every new development or expansion of a city, or even a new city, would be connected and walkable. It will never, by law, be the sprawling suburbs of the vast majority of 20th century (and, it’s sad to say, 21st century) North America. In two simple sentences we could have a system that is incredibly clear, simple to understand, administer, and build.
This won’t guarantee great cities but it will preclude traffic-choked, automobile-dependent ones. With this ordinance you could build Philadelphia. The question we should be asking ourselves is why wouldn’t we do this.
There are, of course, many reasons one can find. But for every one of those reasons, without exception, the result is fewer possibilities for us to have great cities.
One caveat, the number 2,400 feet is not sacred. Each jurisdiction could, and should, change this to suit their needs (think of Portland with 800 foot blocks, or Manhattan at 2,000 feet). The dimension should be the smallest number that accommodates the most varied set of building types. After all, the Empire State Building sits on a parcel of land that has a perimeter of about 1,000 feet, and that’s a pretty big building.