Urban areas used to have edges you could clearly point out. A busy downtown gave way to quieter streets, then farms, then open land. That clean break is getting harder to find.
Today, homes, roads, and businesses stretch outward in uneven patterns. What used to feel separate now overlaps.
The way we think about cities shapes how we build them, how we protect nature, and how people live day to day. When the lines blur, old ways of planning start to fall short.
According to new research, we need to rethink those lines entirely.
Study lead author Steward Pickett is an urban ecologist and scientist emeritus at Cary Institute of Ecosystem Studies.
“There used to be a clear boundary between cities relative to the countryside and the wild, but that has been changing for a long time,” said Pickett.
“You can’t just walk in a straight line from a city center and define where the ‘urban’ ends.”
A patchwork way of seeing places
The study introduces a simple but powerful idea. Instead of labeling areas as urban, rural, or wild, it treats them as blends.
One neighborhood might lean heavily urban, while the next has more trees, farms, or open land mixed in.
“It’s like patchwork or a mosaic,” noted Pickett. “You can have a place that’s 70% urban and 30% rural right next to a place that’s the opposite, or has some wild mixed in.”
This concept is called the continuum of urbanity. It reflects what many people already see around them.
Coyotes show up in suburbs. Gardens grow in city corners. Rural towns adopt city habits, from remote work to online shopping.
How connections shape daily life
These mixed landscapes are not random. They are tied together by movement.
Roads, railways, and even digital networks connect places that once felt far apart. People commute, goods move, and ideas spread quickly.
The Mid-Hudson Valley in New York shows how this works. It includes small cities, farms, and forests, all linked to New York City.
The Hudson River, highways, and train lines keep everything connected. That link affects housing, jobs, and even land use.
Changes that have a cascading effect
During the COVID-19 pandemic, many city residents moved into the valley. Home prices climbed. Forested land faced pressure from new development.
At the same time, online shopping grew, bringing warehouses, truck traffic, and new kinds of work to the area.
These changes don’t stay local. Global trade can introduce pests like the emerald ash borer and spotted lanternfly, which damage forests. Demand for products in one region can drive deforestation in another.
Climate change adds another layer, shifting where people live and how landscapes evolve.
When boundaries create blind spots
Treating areas as strictly urban or rural can hide important details. For example, reconnecting forest patches in suburban areas has helped blacklegged ticks spread, increasing Lyme disease risk.
That kind of outcome is easy to miss if you only look at land in simple categories.
“The message of the Mid-Hudson River Valley case is that familiar urban and rural features are tightly linked,” wrote the researchers.
“One cannot be understood without the other, nor can policies, plans, and interventions neglect the entanglement of the seemingly discrete urban and rural human ecosystem characteristics.”
This way of thinking pushes planners to look at the full picture. A road project, a housing plan, or a conservation effort can ripple across different types of spaces at once.
Four ways to understand a place
The study highlights four areas that shape how mixed landscapes function. These areas help explain what people experience where they live.
Livelihood looks at how people earn a living. A farmer, a warehouse worker, and a remote tech employee may live in the same region but connect to different parts of the economy.
Lifestyle focuses on identity and social ties. The type of home someone chooses or the car they drive can reflect both rural roots and urban influence.
Connectivity goes beyond roads. It includes money, communication, and relationships that link distant places. A family in a rural area might rely on income from someone working in a city across the country.
Location brings these factors together in a specific setting. Geography shapes how all these pieces interact.
Why this shift matters now
This approach changes how decisions get made. It encourages people to slow down and look beyond simple goals like efficiency.
“We hope that the continuum of urbanity encourages people to slow down and think before they design, build, or renovate,” said Pickett.
“For example, someone might want to coordinate the traffic lights to reduce traffic and gasoline consumption. That’s all well and good, but if you only design your city for efficiency, you’re likely to neglect some of the amenities people need for a pleasant, healthy life.
“Our framework slows you down and makes you ask, ‘How’s this going to affect how people live, or where they can recreate, or how they can build social relationships?’ If your profession is an urban ecologist or an urban designer, an urban planner, or a city manager, you have to be aware of all of these components.”
How climate impacts are manifesting
Other researchers are already using this idea. It is helping teams study how green spaces affect both wildlife and people.
The concept is also shaping how experts think about climate risks, especially in areas where development meets natural land.
“The concept provides an extraordinary framework for considering how climate impacts are manifesting within the natural systems that bind the region together,” said study co-author Robert Freudenberg.
“If we are going to plan and manage our way to adapt to climate change, and hopefully avoid its very worst impacts, understanding the ecological interactions that branch across our developed places will be essential.”
A more flexible way forward
The continuum of urbanity is still being refined. Researchers are working out how to measure it and apply it in real-world planning.
But the core idea is clear. Places are not fixed categories. They are mixtures that shift over time.
Study co-author Winslow Hansen is the director of a large collaborative that seeks to reduce the risk of catastrophic fires in the western U.S.
“In my current area of work, we think about the wildland urban interface as a distinct boundary between human communities and wild areas as the epicenter of fire risk,” said Hansen.
“But if you instead embrace a continuum of urbanity, then risk mitigation from fire could become more nuanced, tailored to local ecological and social conditions rather than viewing the world as clearly categorized into one or the other.”
That shift in thinking may not be flashy, but it changes how people approach everyday decisions. It asks a simple question: what if the lines we rely on were never really there to begin with?
The full study was published in the journal npj Urban Sustainability.
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