Research Shows Green Spaces Decrease Violent Crime
The results are even more impressive when community members take part in creating and maintaining them
Hiya!
There is a small scrap of land a few blocks away, nestled between two houses. It was neglected for a long time and grew wild except for a dirt path trodden by locals who used it as a shortcut while walking their dogs. Then, a few years ago, during lockdown, I think, a group of people in the community transformed the wasted space into a community garden and play area for children.
Since then, more public green spaces have appeared, and it seems my area is just one of many communities increasing local greenspaces. Further, research shows these greenspaces do more than just make us take pride in our communities — they also measurably decrease the rate of violent crimes.
Flint, Michigan
Before the water crisis in 2014 that grabbed national attention, Flint, Michigan, was known for its violent crime rate. According to data from the FBI, the Flint Police Department reported 2,774 violent crimes in 2012 — but only 985 were reported in 2022.
So, what’s behind such a substantial drop in violent crime rates? Multiple things, but a big one was the creation of Genesee County Land Bank’s Clean & Green program.
The program’s purpose is to support “innovative community groups and organizations in the cleaning, maintaining, and beautifying of otherwise vacant properties in Genesee County.” Their website lists several accomplishments by the program between its start in 2004 until 2022, including:
“Over 8,200 area residents are estimated to have participated in Clean & Green, including more than 3,575 total area youth and more than 1,550 employed area youth.
The Land Bank has invested more than $5.8 million directly into community-based organizations through Clean & Green.
Clean & Green groups have completed over 275,000 vacant property mowing, valued at $13.7 million.
Nearly 600 vacant houses have been decoratively boarded by Clean & Green groups.”
Researchers are keen to study the Clean & Green program and other similar ones to learn more about the effects they have on their communities.
An exceptionally dedicated researcher is Marc A. Zimmerman, a professor at the University of Michigan School of Public Health who also works as co-director of the Institute for Firearm Injury Prevention and is the principal investigator and director of the Michigan Youth Violence Prevention Center.
In 2018, Zimmerman and his colleagues published a study in the American Journal of Community Psychology. They compared streets in Flint where community members with Clean & Green maintained vacant lots to streets with vacant lots that were left alone for five years, between 2009 and 2013. They discovered the maintained lots had nearly 40 percent fewer violent crimes and assaults.
More recently, in 2023, Zimmerman and colleagues published another study. This one occurred in Flint between 2015 and 2018 and compared violent crime rates between areas where vacant properties are owned and managed by land banks and those not owned by land banks.
(If you don’t know, a land bank is a public authority created to acquire, hold, manage, and develop abandoned, dilapidated, and other properties. They are used to turn these wasted properties into productive community areas.)
The researchers found that areas owned and managed by land banks had fewer firearm crimes, violent crimes, serious crimes, and less crime involving youth victims than those not owned by land banks. I’ll discuss these studies more later on, but Flint isn’t the only area implementing greening programs.
The Rise of Greening Projects
Greening projects are spreading across the United States and the world. New York did a cool one on the West side of Manhattan called High Line, on the remains of an elevated section of a discontinued railway line.
Funded by the NYC Department for Parks & Recreation but operated and maintained by local volunteers, High Line is a nearly 1.5-mile (2 km), wheelchair-accessible public park bursting with over 150,000 trees, shrubs, and flowers.
That’s just the beginning, though. The United States Environmental Protection Agency’s (EPA) Greening America’s Communities Program, formerly Greening America’s Capitals, has assisted 37 communities with sustainable design strategies.
Meanwhile, cities across the world are going green. Austria, Vienna, Copenhagen, Denmark, and Adelaide, Australia, are considered the greenest cities worldwide.
More Research
Zimmerman is only one of many researchers studying the effects of greening spaces, and a decrease in violent crimes is almost always the top impact these spaces have on the communities they’re in. Zimmerman told National Geographic:
“It is one of the most consistent findings I’ve ever had in my 34-year career of doing research.”
One look at his research makes that clear. Yet another study involving Zimmerman, this one from 2022, found that areas around vacant lots in Flint that were cared for by community residents experienced over twice the reduction in violent crime compared to professionally maintained areas. Meanwhile, areas that received no care saw a slight increase in violent crime.
However, the effects extend beyond Flint, Michigan. In 2019, a team of researchers reviewed 45 papers examining the relationships between green spaces and crime rates in communities. They concluded: “Based on the 45 quantitative and qualitative papers summarized here, we can deduce that the presence of parks and other green space reduces urban crime.”
In Zimmerman’s 2022 study, the researchers found that street segments in Youngstown, Ohio, with professionally mowed vacant lots, showed a decrease in violent crime density compared to the control lots. And segments greened through community engagement showed even sharper declines.
Way back in 2011, researchers in Philadelphia, Pennsylvania, found a link between planting trees and grass and a slight decrease in vandalism and a consistent drop in gun assaults. Vacant lot greening was also associated with locals reporting less stress and more exercise in select city sections.
A 2018 study involved 342 participants greenerizing (I totally made that word up, but I’m sticking with it) 110 randomly selected vacant lots in Philadelphia. The “greening intervention,” as the researchers call it, involved the participants completing various tasks like picking up trash, planting new grass or trees, installing a simple perimeter fence, and performing regular monthly maintenance — or performing no tasks in the case of the control group. By the end, they found:
“The remediation of vacant and dilapidated physical environments, particularly in resource-limited urban settings, can be an important tool for communities to address mental health problems, alongside other patient-level treatments.”
In addition to less violent crime, a different 2022 study involving Zimmerman found that greening lowers rates of child maltreatment.
How it Works
By now, it’s clear that creating and maintaining green spaces bring positive changes to communities, especially in decreasing crime rates. But researchers also want to know why it happens. Zimmerman believes it has to do with the “broken windows” and “busy streets” theories — which was the focus of the 2018 study Zimmerman was part of.
Zimmerman explains to National Geographic that the idea behind the broken windows theory is that when an area has broken windows, even just one, it sends the message “that nobody’s watching, that you can get away with things, and you can do nefarious activities, and nobody cares.”
Meanwhile, the busy streets theory is the opposite. It says that residents who engage in revitalizing their neighborhoods help form an empowering sense of community, which tells people who are thinking of committing a crime “that people are paying attention and care about this place.”
Beyond a sense of safety, Zimmerman says,
“From our research, it helps people feel better about each other, about themselves, about their neighborhood, about their community, about their street.”
And it seems youth engagement is vital to the success of greening programs in reducing crime. Six greening organizations Zimmer and his colleagues interviewed all stated that youth voices are crucial to their cause.
In Flint, founder of the nonprofit CHANGE Foundation, Darnell Ishmel, introduces youth to Clean & Green and says it’s easy to see “the pride on their faces, for putting on their Clean & Green shirts and going out with their tools and their gloves and actually doing something… positive for their neighborhood.”
Even better, other research Zimmerman was involved in (from 2015) discovered that greening projects are contagious, like an infectious laugh. People living near greenerized lots start improving their own yards, too.
In the Future
Zimmerman and his colleagues aren’t anywhere near done researching and have several more projects already underway.
They will continue to measure health outcomes in Flint, but are also working alongside Keep Indianapolis Beautiful to study the long-term effects of greening projects. Meanwhile, in Detroit, they’re comparing the effects of different greening projects — such as community gardens, mowing, mini-parks, and public art — to see if any of them influence violent crime rates more than others.
Hopefully, as more communities greenerize vacant spaces and crime decreases, greening projects will become habitual and allow the positive effects to ripple across generations. But we can go further. As greenerizing spreads and grows, it could lead to creating more sustainable cities, and then maybe countries.
Perspective Shift
I don’t know if members of my neighborhood were inspired by the greenerized transformation of the little wasted lot, but I’ve noticed residents stepping up their landscaping game in the years since.
Now, many houses in my neighborhood seem to be partaking in the native yard trend — which is so cool — by replacing their grassy lawns with native plants. It might not seem like much, but when multiple houses in a row do it, it can feel like you’re walking in nature while walking down the street. Sometimes, I don’t even notice the houses tucked behind.
I like to imagine what it could be like if most or all grassy yards were replaced with native plants. Maybe we’d become more peaceful as a byproduct if all communities participated in greening projects. It seems like a fantastic way to integrate nature into our cities and lives, and we all know that being in nature does wonders for our health.
Encouraging!