Elegant Graphs Reduce 25 American Cities to Their Design Essence

And show what Boston and Charlotte have in common.

The sun sets on the axis of 42nd Street in Manhattan.
Tonight is the night the city planners come alive.

Geographer Geoff Boeing, an urban planning postdoc at UC Berkeley, has found a way to represent a city in a handy visual shorthand. By downloading and crunching municipal boundaries and street networks from OpenStreetMap, Boeing has assembled handy histograms that show the distribution of the orientations of a city’s streets around the points of a compass.

Consider the exceptionally gridded terrain of Tampa, Florida, where nearly every street runs north-south or east-west. As a histogram, it’s a perfect compass.

A histogram showing the street orientation in Tampa.
Geoff Boeing

A city where separate grids connect, like St. Louis, looks a little noisier.

A histogram showing the street orientation in St. Louis.
Geoff Boeing

Among Boeing’s conclusions? It’s Charlotte, North Carolina—that sprawling Sun Belt metropolis not known for its charming, cozy urban spaces—that most closely resembles the tangled street grids of Paris or London.

First, though, the easy stuff: Grids predominate in American cities. Some of the older ones east of the Ohio River—Manhattan, Philadelphia, Washington D.C.—were built by forward-thinking city planners. Others were shaped by Thomas Jefferson’s imposition of a rectangular grid, which made it easy to distribute, sell, consolidate and speculate on land. That Jeffersonian grid is visible from any airplane crossing the agricultural terrain of the Great Plains, but it’s also easily discerned in the urban terrain of Southern California. (And lots of other places too!)

A selection of histograms showing street orientation.
Geoff Boeing

A handful of these histograms serve as shorthands for urban history—in Detroit, for example, a compass-rose-style histogram shows how the city’s initial orientation towards its riverfront gave way to the north-south Jeffersonian grid.

A map of Detroit alongside a histogram of street orientation.
Geoff Boeing

This is even true in postwar cities riddled with suburban cul-de-sacs. “In places like Orlando and Phoenix, once you get inside of the gridded superblocks, you do see curving streets,” Boeing says. But because his algorithm measures the angle between the two closest intersections—without regard to the twists and turns between—these set-ups tend to register as more orthogonal than they look on a map. Histograms of true suburbs, like Moraga, California, in the hills of the East Bay, show a more expected “eyeball” pattern.

The value of the grid is well-established in city planning going back to Roman times. “The aboveground order of a grid city facilitates its underground order in the layout of water pipes, storm drains, sewers, electric cables, natural gas lines, and subways—an order no less important to the administrators of a city,” James Scott wrote in his 1998 book Seeing Like a State. “Delivering mail, collecting taxes, conducting a census, moving supplies and people in an out of the city, putting down a riot or insurrection, digging for pipes and sewer lines, finding a felon or conscript (provided he is at the address given), and planning public transportation, water supply, and trash removal are all made vastly simpler by the logic of the grid.”

But, of course, it also requires a degree of foresight—and a cocky disdain for topography—that can be hard to put into practice. Boeing’s visualization nicely captures the feeling of being hopelessly lost in Boston, one of America’s earliest big cities.

A histogram of street orientation in Boston
Geoff Boeing

The only other American city, among the 25 Boeing analyzed, that compares to Boston is … Charlotte. The core of the city is a neat grid, but it dissolves into a pattern that looks like cacio e pepe served on a bicycle wheel. What gives Charlotte this inscrutable layout? Three things.
First, it didn’t grow fast enough during the 18th century to receive a great, forward-thinking grid plan like Manhattan or Washington. Second, its suburban framework is composed of old roads that once connected the city center to outlying villages. No Jeffersonian grid was ever imposed here. “It looks like spokes of a wheel, and those spokes are the naturally occurring farm roads converging on the courthouse,” says Tom Hanchett, a Charlotte historian and author of Sorting Out the New South City.

A histogram showing the orientation of streets in Charlotte.
Geoff Boeing

Third, Charlotte managed to keep expanding, absorbing the spaghetti-grids of suburban developments. The tight city limits of Atlanta, by contrast, meant Boeing’s sample represents a much smaller fraction of the Atlanta metro area.

Thursday night marks Manhattanhenge, the biannual spectacle in which the setting sun is perfectly framed by Manhattan island’s crosstown streets, filling the city’s skyscraper canyons with orange light. Most cities will have their henge-day, though most don’t have tall enough buildings or narrow enough streets to create an impressive effect. More likely, the alignment just blinds drivers on their way home from dinner.

Charlotte and Boston, though, have no citywide summer sunsets, just like the grid-less cities that are common elsewhere in the world, including Rome, Seoul, Hong Kong, and Rio de Janeiro.

A histogram of world cities by street orientation
Geoff Boeing