Starting mainly in the 1960s, cities in the industrial Midwest and Northeast experienced manufacturing plant closures that resulted in significant job losses and economic decline. The loss of industry and incentives that encouraged suburbanization led to migration out of city centers (Dewar & Thomas, 2013). These trends, along with discriminatory lending practices (i.e., redlining), have led to deepening economic disinvestment and inequities experienced by the predominantly residents of color remaining in city centers (Dewar & Thomas, 2013; Lowe & Thaden, 2016). In recent decades, demolition has been a widely adopted, federally funded strategy to address deteriorating abandoned buildings in cities with a concentrated vacancy (U.S. Department of the Treasury, 2019). While demolition may be an efficient solution to some immediate safety risks associated with abandoned buildings (Spelman, 1993), if the resulting vacant lots created by mass demolition are not adequately managed and maintained, they can potentially become larger liabilities and hotspots for crime and violence (Branas et al., 2013). Neglected vacant lots often become crime attractors, increasing opportunities for activities that are unwanted by communities and providing hiding places for illegal weapons (Branas et al., 2013, 2018; Garvin et al., 2013). In a national survey of organizations charged with managing vacant properties, nearly two-thirds reported that their inventories of vacant lots have expanded over the past two years (O’Keefe et al., 2020). Structure-free vacant lots now make up 75% of vacant property inventories nationally, as compared to vacant buildings (only 25%). The vacant lots left behind after demolition are so numerous that organizations widely report they are unable to adequately maintain them with the limited funding available for vacant lot greening (O’Keefe et al., 2020). As a result, postindustrial cities across the United States are confronting a growing challenge of unmaintained vacant lots that can lead to violence and crime (Garvin et al., 2013; O’Keefe et al., 2020).

Vacant and neglected urban properties are associated with negative residential outcomes, such as increased perceptions of social disorder (Ross & Mirowsky, 1999; Taylor et al., 1985), fear of crime (Branas et al., 2018; Ross & Mirowsky, 1999), mental distress (South et al., 2018), and aggression in young males (Diez Roux & Mair, 2010; O’Brien Caughy et al., 2012). Indicators of physical deterioration (e.g., abandoned buildings) and vacancy (e.g., neglected empty lots) are also associated with crime, low neighborhood satisfaction, poor health outcomes, and reduced neighborhood investment (Branas et al., 2013; Dassopoulos et al., 2012; Immergluck & Smith, 2006).

Researchers have reported that improving vacant lots through greening can help to transform a neighborhood (Bowman & Pagano, 2000, 2004) and that well-maintained natural areas may improve physical and mental health (Branas et al., 2011; Groenewegen et al., 2006; South et al., 2015), and reduce fear of crime and violence (Branas et al., 2011, 2018; Burt et al., 2021; South et al., 2018). Greening is the process of restoring the landscaping and appearance of a vacant lot by mowing and maintaining it to control growth (Krusky et al., 2015). Greening can include simple measures such as cleaning, mowing, and maintaining vacant spaces, or more involved applications such as community gardens (O’Keefe et al., 2020). Residents have reported feeling safer when they were in open, mowed areas compared to densely vegetated, overgrown areas (Schroeder & Anderson, 1984). Resident fear of crime decreases as a function of open sight lines resulting from the removal of overgrown vegetation (Kuo & Sullivan, 2001). In a randomized control trial, residents living near newly greened lots reported reduced perceptions of crime, nuisances, and safety concerns than those living farther away (Branas et al., 2018). In this trial, they also found that police-reported crime, burglary, and gun violence decreased in areas with newly greened lots, which supports prior, controlled observation studies (Kondo et al., 2016). These findings are consistent with the Busy Streets Theory (BST).

BST posits that thriving urban spaces are those that include orderly, safe physical environments, socially connected and engaged residents, and positive neighborhood activity (Aiyer et al., 2015; Heinze et al., 2018). Improving physical conditions by greening and repurposing vacant lots may be one way to create safer neighborhoods as it signals social control and reduces residents’ subjective perceptions of crime (Branas et al., 2018; Burt et al., 2021), and creates opportunities for health-promoting physical and social activities (De Sousa, 2014; Németh & Langhorst, 2014). Safety may be enhanced when residents work together to improve their neighborhoods because positive interactions help restore neighborhood relationships and community connectedness, which can attenuate crime and violence (Aiyer et al., 2015; Stafford et al., 2007).

Engaging residents in cleaning up, planting, and maintaining vacant urban properties may have positive effects on residents’ mental and physical health, and reduce crime and violence because it sends the message that people in the neighborhood care about the area. In our prior work, we found that involvement in neighborhood gardens and beautification activities increased social capital, social support, neighborhood satisfaction, and informal social control, and improved intergenerational relationships (Alaimo et al., 2005). Residents involved in greening have also reported decreased litter, increased neighborhood interest and community pride (Alaimo et al., 2010), and an enhanced sense of community ownership (Rupp et al., 2020).

In the context of urban environments that experience a concentrated vacancy, significant structural disadvantage, and high rates of crime, community-engaged greening to improve the physical characteristics of a neighborhood may be one way to create busy streets. Community-engaged greening refers to collective greening efforts that involve residents working together to remediate and improve the appearance of vacant and neglected lots in their neighborhood. Community-engaged greening involves residents in the planning and implementation of greening projects such as mowing lots, planting a garden, or other vacant lot reuses (e.g., pocket park). Such an approach is promising for its potential to promote busy streets, where combining greening and community engagement may benefit crime and violence prevention above and beyond the greening treatment alone.

Yet, thus far, few researchers have used multiple study conditions to examine the potential effects of resident engagement in greening for crime and violence prevention. Heinze et al. (2018) found that street segments receiving vacant lot mowing performed by community groups in Flint, MI, reported a 40% reduction in assaults relative to street segments with vacant lots receiving no maintenance, but they did not consider professional mowing in their evaluation. Kondo et al. (2016) evaluated the association between both resident-led and professional contractor-led landscaping and crime, but they did not randomly assign professional and control conditions, nor did they focus on youth-specific crime or violence. We build upon the findings of these studies with our study by comparing the effects of community-engaged greening, professional mowing, and no greening intervention.

In this study, we examine the longitudinal association of three greening conditions implemented from 2016 to 2018 in Youngstown, OH, with violent crimes committed against people of all ages, as well as only youth. We use victimization as our outcome because this is the most complete data—police incident data have significant missingness regarding who committed acts of violence (over 50%). We intentionally compared the effects of community-engaged greening against professional mowing and hypothesized that community-engaged greening would be more effective in reducing violence and creating safer neighborhoods because it incorporates the previously described social benefits of resident engagement into greening for violence prevention. We also hypothesized that both greening strategies would be more effective in reducing violent crime and youth-related violence than no greening activity. We tested these hypotheses in a Midwestern city that has experienced significant disinvestment and physical decline in past decades.

Table 1 displays descriptive statistics of all study variables across cohort year and treatment condition for our selected sample of street segments. We count the number of intervention parcels per cohort year and treatment condition and show the number of street segments selected from buffers around our intervention parcels. We also summarize our outcome variable (Part 1 crime density per street segment for all victims and youth victims), and our census control variables. Figure 2 shows the mean youth Part 1 crime density for each greening condition by month, aggregated from 2016 to 2018.

Two-sample t tests (results not shown) to test the equivalence of conditions on the control variables indicate statistically significant differences in the population density across the three treatment conditions: professional mow areas had the lowest average population density, and no treatment control areas had the highest average population density. Additionally, street segments in the no treatment control condition had a higher average disadvantage index than street segments within the professional mow condition and street segments in the community-engaged greening condition. We found no differences in neighborhood disadvantage between professional mow and community-engaged greening street segments.

Table 2 summarizes the regression coefficients of our constructed model, which predict monthly Part 1 violent crime density for all victims over the course of the summer during each of the study years. In Model 1, we predicted crime density via our control variables with a random effect for the intervention parcel associated with each street segment. Population density (β^=.00038, p < .001), neighborhood disadvantage (β^=6.24, p < .001), and spatially lagged crime density (β^=.92, p < .001) all predicted violent crime. Model 2 included a time (month) predictor and a random effect for year. In Model 3, we added a main effect for greening condition, and in Model 4, we included an interaction effect between greening condition and month to model the different summer crime density trends between greening conditions.

The coefficients for the main effect predictors of the greening condition in Model 4 show a positive association between community-engaged greening street segments (compared to control segments) and violent crime (0.69 more incidents/mi²), and a negative association between professional mow street segments (compared to control segments) and violent crime (0.72 less incidents/mi²), though these associations were not statistically significant. The coefficient for month was positive, indicating that as the summer progresses, we expect a slight increase in violent crime density (0.098 more incidents/mi² each month, p < .05). The larger negative interaction coefficients between month and greening condition for both community-engaged and professional mow classifications indicates, however, that as the summer progressed we found a decrease in Part 1 violent crime density for these noncontrol street segments. Notably, community-engaged greening street segments had a larger decrease (β^=−.36, p < .001) than professional mow street segments (β^=−.16, p < .05). When we changed the reference condition within our models from control to professional mow to compare community-engaged greening street segments and professional mow street segments, we found the community-engaged greening condition and month interaction effect indicated larger decreases in violent crime incidents (β^=−.20, p < .05). Additionally, as shown in our tables, the standard errors of the coefficients for these conditions do not overlap.

We found similar results when considering Part 1 violent crimes involving youth victims using the same analytic approach as above. Effect estimates are shown in Table 3. Again, while the association between violent crime density and intervention condition for professional mows and community-engaged greening were positive though not statistically significant (β^=.48 and β^=.11 respectively), the coefficients for the interaction between both community-engaged conditions (β^=−.23, p < .001) and professional mow conditions (β^=−.097, p < .001) and violent crime were negative and signibcant. We changed the model reference condition from control to professional mow, and again found that community-engaged greening street segments showed larger decreases in violent crime incidents compared to professional mow street segments β^=−.13, p < .01).

In both Tables 2 and 3, we find that all model intercepts are negative. This is a result of the neighborhood characteristic control variables (disadvantage index and population density) within the models, as their values are 5-year aggregates that do not have any variation within a street segment between months or years. Though the explicit intercept value is not interpretable when negative, the units of the model coefficients are still consistent with our outcome variable (i.e., crime incident density per square mile).

Table 4 shows the results of our displacement analysis for Part 1 violent crime against all victims and for youth victims only. Though we found differences between the violent crime trends of the displacement areas and control areas in some years, we do not see an increase in violent crime in our displacement areas. In the displacement areas, violent crime trends tended to be more negative each year across the summer months than in control areas, which could be explained by further radiating effects of the greening intervention.

Our findings support the BST: community-engaged greening of vacant lots in postindustrial cities with a concentrated vacancy can reduce violence. This is evidenced by our finding that street segments around vacant lots cared for by community residents (i.e., community-engaged greening) had greater reductions in violent crime density for victims of all ages, as well as specifically youth victims, over the course of the summer, compared to lots that had no greening activity or that were mowed by professionals. The association between professional mow areas and a greater reduction in crime over the summer compared to the control areas adds to prior evidence supporting property maintenance and greening as a crime reduction strategy (Branas et al., 2018; Heinze et al., 2018; Kondo et al., 2016). The stronger effects of community-engaged greening compared to professional mowing could be accounted for in the active participation of residents in neighborhood activity, creating ongoing attention to the area (e.g., maintaining gardens or parks, neighbor interactions while working on the lot) that would not occur when professionals only mow sporadically. This ongoing activity helps create a busier street that is a less inviting environment for criminal and other nefarious activity.

The community-engaged greening effects that we observed may be due to an improvement in community relationships and engagement. Residents involved in greening have reported feeling better about—and more efficacious to make changes in—their neighborhood and more connected to their neighbors (Alaimo et al., 2010; Rupp et al., 2020). Participants in greening projects have reported advocating for organizational and municipal policies to support their activities, resulting in a city composting program, watershed improvements to reduce flooding, and the use of native plantings on city-owned properties (Reischl et al., 2010). Expanded involvement of community residents in greening can have a contagious effect, as witnessing neighbors implementing neighborhood improvements may encourage residents to increase their own property maintenance to meet a higher standard of care (Krusky et al., 2015; Rupp et al., 2020; Troy et al., 2016). The development of new social resources and norms for maintenance may signal greater social control and help to attenuate crime and violence.

Our confidence in the results is strengthened by several factors. First, we observed associations between the professional mow and community-engaged greening conditions, timing, and violent crime even when controlling for population size, neighborhood disadvantage, and existing neighborhood crime. Second, our outcome variable does not suffer from self-report bias. It is also likely that given our focus on violent crimes which are relatively rare, our analysis is a conservative test of the effectiveness of the greening interventions on other crime and psychological outcomes found by other researchers (Branas et al., 2018; Kondo et al., 2016; Rupp et al., 2020; South et al., 2018). Third, our study incorporated random assignment of the professional mowed and control conditions. This random assignment helped to reduce some potential unmeasured confounding factors between these two conditions, such as greater police activity or community organization social events, that may explain the results. Fourth, the use of the street segment as our unit of analysis also generalizes the effects of the greening condition to a larger level than a specific parcel on the street. It also allowed us to more directly test BST because our analysis incorporated both the vacant lots and the surrounding social environments where more social activity, support, and capital could occur. The similarities in our model results for violent crime with victims of all ages compared to youth victims suggest that these findings are consistent for different methods of defining the dependent variable, particularly given that the smaller number of youth crimes reduces the amount of variance that could be explained (vs. all ages).

Another concern regarding greening interventions is that they simply displace crime from one area to another and do not prevent crime. Yet, similar to previous studies (Branas et al., 2018), our displacement analyses suggest otherwise. We did not find an increase in crime in areas adjacent to the intervention areas and crime trends tended to be more negative each year across the summer months than in control areas in these analyses.

Our results support the notion that community-engaged greening can be an effective way to reduce community crime and violence. They are consistent with other researchers who have reported similar effects for general greening and particularly community-engaged greening and are consonant with BST. Our study builds on past work by including a focus on youth violence, comparing professional mowing versus community-engaged greening, and randomly assigning professional mow and control conditions. Greening interventions driven by community residents can be readily scalable to cover large areas, affect population-level change for improving community health and preventing violence, and are sustainable over time when they receive sufficient economic support (Branas & Macdonald, 2014; Frieden, 2010). Yet, it is also vital not to hold local residents wholly responsible for the quality of their neighborhoods, as many factors beyond individual and neighborhood control often drive the economic and policy decisions that result in neighborhood neglect and breakdown of social controls. In our research, we have found that resident engagement is vital to the sustainability of greening as it is associated with enhanced acceptability of programs, long-term buy-in and resident control of programs, and enhanced organizational functioning (O’Keefe et al., 2021; Rupp et al., 2021). When asking residents to participate in vacant lot care, however, Lowe and Thaden (2016) suggest that there is potential for community burn out when residents are asked to do too much with too few resources to support their work (Lowe & Thaden, 2016). Partnerships with local organizations (e.g., neighborhood associations) and institutions (e.g., local foundations, land banks) can help residents sustain locally driven greening programs by leveraging the capacity and resources necessary to maintain vacant properties. Policies that help organizations more efficiently acquire vacant properties before they enter tax auction are also vital to the capacity and sustainability of greening programs. These policies help organizations reclaim properties so they can maintain or repurpose them for community-driven needs before they deteriorate or are purchased by speculative buyers who frequently neglect them (Alexander, 2015; O’Keefe et al., 2021). Our results suggest that efforts emphasizing the collaboration of local organizations and institutions with residents for community improvement can assist residents in taking back their neighborhoods, and are a first step toward providing the support necessary to maintain and sustain busy streets.