A little more than a century ago, large numbers of automobiles began to hit Canadian streets. Their arrival ushered in new ideas about how to design our cities – ideas whose unfortunate consequences remain to this day.

Whereas the premotorized city was a place where life was conducted mostly on foot, in local neighbourhoods, the 20th-century city was imagined as a compartmentalized entity, with each of life’s activities – living, shopping, working – in a separate part of town. American city planner Harland Bartholomew was prominent among such proponents of strict zoning, underpinned by the primacy of the car.

Mr. Bartholomew made one major foray into Canada, when he delivered a tome of a Vancouver city plan in 1928. A core pillar: “A city of single-family homes.”

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Nine decades later, that thinking still defines Vancouver, and to some extent all Canadian cities. But change is coming, with tentative steps taken at city councils from Vancouver to Toronto. Early plans include the idea of reintroducing traditional corner stores to residential-only areas, and different types of housing in neighbourhoods long reserved for single-family homes.

As with all movements, this one has a buzzy catchphrase: the 15-minute city. The branding is new; the ideas are not. They hark back to a time before cities were cut up by car-centric planning.

The core idea is simple: Everyone should be able to meet their daily needs within 15 minutes of home, on foot or bike.

That is already a reality in the oldest parts of Canadian cities, from central Montreal and Toronto, to Vancouver’s downtown peninsula. For most everyone else, life is defined by the car.

The 15-minute flag has been waved most enthusiastically by Paris Mayor Anne Hidalgo. Her “Ville du 1/4hplatform – “city of a quarter hour” – was a centrepiece of her re-election this year. Among Ms. Hidalgo’s ideas is a bike path on every street.

This push to rethink cities is about two things.

The first is how life can best be lived and enjoyed. What’s loved about the most successful cities is their vibrant streets and neighbourhoods. When planning began to focus on the car, and assumed that people should not live where they shopped or worked, such streets and neighbourhoods become impossible.

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The second is climate change. A sprawling city is very energy intensive.

In mid-July, a coalition of 96 leading cities around the world, dubbed the C40 Cities, put out its “green and just recovery” plan. The 15-minute city is a key part of the agenda. Cities such as Portland, Ore., and Melbourne have been already working on “20-minute neighbourhoods.” And in recent years, the market has been sending a clear signal. Across North America, homes in walkable neighbourhoods are at a premium. Smart Growth America, a U.S. advocacy group, argues this indicates there is “not nearly enough supply.”

This lack of supply is artificially enforced by zoning – going all the way back to the early 20th century, and people such as Mr. Bartholomew.

Cities will not instantly transform, but they are already evolving.

The first steps are small. Vancouver, in the midst of a city planning process that will stretch to 2022, is looking at the revival of corner stores. City council in late June asked city staff to come up with a crop of ideas by this fall. In Toronto, the city is looking at allowing new housing options in neighbourhoods long reserved for single-family homes. The process, as in Vancouver, is ponderous, and it could be years before we see any real change.

Above all, cities need to make room for experiments. Zoning is often about rigidity, whereas the best cities are fluid when it comes to land use. It’s time to rescind longstanding restrictions and open up options. Shouldn’t a modern corner store, small local commercial spaces on four corners, and low-rise apartments be welcome in every neighbourhood? Do we really need so much parking?

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Civic planning rules from Mr. Bartholomew’s era prescribed how a city should be, and made way for only single outcomes. The 15-minute city, at its heart, is about less planning, not more, freeing people to imagine what a city can be. It can lead us to more diverse and vibrant cities.

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