MSU Research Suggests Homicide Rates Decline as City Greenery Increases

October 28, 2021

Chicago park; Photo by Eliyah Reygaerts on Unsplash

For many of us, being surrounded by nature can not only be a soothing experience, an excellent way to relieve stress, and improve our physical and mental health, but recent research conducted by Michigan State University researchers suggests that nature may also help reduce violent crime. A recent study led by MSU Geography Ph.D. student Jonnell Sanciangco sought to determine whether increases in greenery in the United States predicted fewer homicides over a 30-year time span.

Looking at 290 American cities within 45 different states between 1986 and 2015, the team utilized a variety of data, including census, climate, and FBI data on murder and non-negligent manslaughter. The team also measured the level of greenness for each city from the 1990s through 2015.

By compiling and accounting for any variables that risked confounding the association between city greenness and homicide rates, through their statistical analysis, the team saw declines in homicides from 1990 to 2015 in 218 of the 290 cities examined. The most significant declines were found in Washington, D.C.; Atlanta, Georgia; and Richmond, Virginia.

Over half of all cities studied slightly increased their average greenness during the time period studied, and these increases in greenness appeared to correlate with declining homicide rates. In a paper outlining their findings in the September 2021 edition of Environment and Behavior, the team argues that nature's restorative effects on cognition help revive self-control, and the more collective self-control among a city's population can mean a lower likelihood of violence. In addition, the team also postulates that the more pleasant an environment is, the more people living nearby will take proactive steps to surveil the area and report or suppress behaviors that threaten to damage the sanctity of the area. Such efforts may lead to a reduction of crime while also inspiring residents to promote and defend the safety of their neighborhoods.

In addition to Sanciangco, the team was made up of several MSU researchers, including Zihan Lin, Yuhao Wang, and Amber Pearson. Additional authors include Gregory Breetzke from the University of Pretoria and Kimberly Clevenger with the National Cancer Institute.

The team's research was recently featured in an article written by Katherine Schrelber for Psychology Today. The original publication in the journal Environment and Behavior can also be accessed here.