It's strange to realize you're provincial, even though your province is New York City. Last week I was giving directions to a British tourist on the street and said "…that's about ten blocks away" when she startled me by saying "We don't do 'blocks'—what's a 'block?'"

Afterwards I recalled London's spaghetti-like cartography and realized that, of course, 'blocks' would make no sense there. I subsequently asked a Londoner friend how they relate distances for urban directions, and he said they either use landmarks, pubs (ha), terms like "three streets down" or meters.

I'm reminded of this by looking at the work of Geoff Boeing, a PhD candidate in Urban Planning at U.C. Berkeley. Boeing is a fan of Allan Jacob's 1993 "Great Streets," which asked the question "Which are the world's best streets, and what are the physical, designable characteristics that make them great?" to find out, Jacobs created one-square-mile maps of 50 different cities around the world, allowing the reader to easily see the visual differences:

For his dissertation, Boeing has expanded on Jacobs' work by coding up a Python-based package called OSMnx. It allows you to "download a street network from OpenStreetMap for anywhere in the world in just one line of code," making it easy to compare, at the same scale, different layouts. Some examples:

The top row depicts the late 19th century orthogonal grids of Portland, Oregon and San Francisco, California. Portland's famously compact walkable blocks are clearly visible but its grid is interrupted by the Interstate 405 which tore through the central city in the 1960s. In the bottom row, the business park in suburban Irvine, California demonstrates the coarse-grained, modernist, auto-centric urban form that characterized American urbanization in the latter half of the 20th century. In stark contrast, Rome has a fine-grained, complex, organic form evolved over millennia of self-organization and urban planning.

Above, we see New York, Paris, Tunis, and Atlanta. Manhattan's rectangular grid originates from the New York Commissioners' Plan of 1811. You can see Broadway weaving diagonally across it. At the center of the Paris square mile lies the Arc de Triomphe, from which Baron Haussmann's streets radiate outward, remnants of his massive demolition and renovation of 19th century Paris. At the center of the Tunis square mile lies its Medina, with a complex urban fabric that evolved over the middle ages. Finally, Atlanta is typical of many American downtowns: fairly coarse-grained, disconnected, and surrounded by freeways.

You can read more by Boeing and/or start using OSMnx here.

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