Frank Lloyd Wright’s Broadacre City (Image from CityLab)
Whether I’m day dreaming out the window at my office or walking around running errands, I think a lot about the shape of the city. I am fascinated by the intersection of humanity, capitalism, and nature. Before building a city, us humans see a landscape with lakes, rivers, forests, hills, and valleys. For better or worse, we bridge the rivers, we flatten hills, we shape the shoreline, and we carve streets into the hillside. While we try to follow a plan - usually a grid - we often end up with a smorgasbord of layouts. Throughout this network of streets, we build all sorts of buildings shaped by the funny confluence of economics, policy, and aesthetics. While the natural world that we bulldozed emerges here and there in our parks, the weeds cracking through a sidewalk, and the bunnies procreating in my neighborhood, the business of human life builds through decades of routine. People make simple choices: What’s the fastest route to my job? What’s the most convenient form of transportation available? How far am I willing to walk for a little errand? These little decisions have huge consequences into how the city is laid out, valued, and built. And none of this is a straight-line: it’s a messy, beautiful mixture of many forces working in all sorts of ways we don’t understand.
I recently read this fascinating article in CityLab called The Commuting Principle That Shaped Urban History by Jonathan English. English explores the idea of the Marchetti Constant - the principle that most people are willing to commute 30 minutes to their job each day. In practice, this means “that the physical size of cities is a function of the speed of the transportation technologies that are available.” From ancient Rome to medieval European cities, the dimensions of the city were determined by how far someone could walk in 30 min - about a 1 mile radius. Fast forward to the 18th century when trains and streetcars were introduced to cities like Chicago and Philadelphia - now the city could grow in scale to accommodate new commuting technologies. Then skip to the mid-1950s when cities grew by another order of magnitude… this time determined by the scope of their freeways and automobile infrastructure. The car reigned supreme for half a century and created cities of massive sprawl.
The growth of cities based on the technology most people used to commute. (Image from CityLab)
The fascinating Marchetti Constant renders one of the many complex factors that shape our cities into an incredibly simple rule - a 30-minute commute. Although this phenomenon is based on quantitative data about the sizes of cities over time, if you look at it the other way, it suggests that a 30-minute commute is one that is reasonable and satisfactory for most people. More urban planning principles should be grounded in beliefs about a satisfactory city life - What is a reasonable proximity to parks? To public transit? To shops and restaurants? And to our neighbors? - instead of around which technologies are the most efficient or groundbreaking.
But when we do pause to think about the technologies that shape our cities, it’s clear we have to take a step back from cars. Since cities with robust public transit and pedestrian and bike access are not only more sustainable but so much more pleasant to live in, it is time for a fundamental rethinking of the shape and size of our cities.
Recreating History
Seattle of 1908 (Image from the Seattle Times)
Seattle of 2019 (Image from the Seattle Times)
While on the topic of cities and change, I also wanted to give a shout out to a semi-regular feature in the Seattle Times that I love. It compares historical photographs with their modern day equivalent. I loved the image that was shared today. In a city changing as quickly as Seattle, it’s sometimes hard to imagine the city 20 years ago and it’s nearly impossible to recognize the Seattle of 1908, but it’s wonderful to imagine what it would have been like. So many things we take for granted - how did you even get to Mercer Island without the bridge!? - are not yet built. Comparing the historical photograph taken somewhere in Fremont with the modern recreation, not only are the forests gone and the shoreline changed, but an entire bridge is blocking the view! In fact, the Seattle Times photographer describes how it is impossible to perfectly recreate the photograph because of the buildings and physical changes! Wow - how fast the city changes! I can’t wait to imagine the next 20 years!