Current Research Projects

Mass Incarceration, Racial Segregation, and Spillover Effects in U.S. Communities

This project investigates the causes and consequences of mass incarceration within U.S. communities and neighborhoods. The overarching goal is to study how residential inequalities drive incarceration rates and disparities, and how neighborhood exposures to the criminal justice system affect the well-being and political participation of community members. The first part of the project evaluates and tests place-based mechanisms, specifically segregation and housing conditions, that may be driving disparities between demographic groups and shifts in incarceration over time. This part of the study seeks to understand how contemporary incarceration rates and disparities emerge from both historical residential patterns and recent changes in U.S. communities. The second part of the project examines how multiple, interrelated criminal justice system exposures, from contact to imprisonment, may accumulate to affect community well-being and political participation. An open criminal justice data project establishes a replicable system of data collection, processing, archiving, and analysis that coincides with an interdisciplinary educational program of courses, practicums, and symposia. The integrated research and educational aims of this project expand the participation of underserved students in STEM, share newly collected data on criminal justice exposures with the public, and provide useful insights for interventions addressing inequality and mass incarceration.

To better understand rates of and disparities in criminal justice contact, as well as their influence on community well-being and democratic membership, this project focuses on the measurement and influence of place-based mechanisms?specifically, residential segregation and neighborhood effects. The two studies that comprise this project integrate data science methodologies, machine learning, spatial analysis, and quasi-experimental design to test theories relating segregation to mass incarceration and community-level spillover effects. To do so, these studies combine rarely accessible geocoded data on policing and incarceration with detailed individual-level data on voting and mortality. By combining top-down sociological theories of place and punishment with bottom-up data science and machine-learning techniques, this project brings new evidence to bear on these theories and contributes synergistic new methods to the fields of sociology, data science, and their application.

This set of projects is funded by a National Science Foundation Faculty Early Career Development Program (CAREER) Award, a five-year grant in support of early-career faculty who have the potential to serve as academic role models in research and education.


Simes, Jessica T. "Stability and Change in the Spatial Context of Mass Incarceration." Working Paper.

The Consequences of Ending Cash Bail for Community Health Equity

Nearly 500,000 legally innocent people in the U.S. are currently in pretrial detention. The inability to afford bail prevents many from being released from jail pretrial, disproportionately impacting Black Americans and people living in poverty. Recent cash bail policies have been aimed at eliminating financial barriers to bail and reducing jail incarceration. This includes policies in New Jersey, which in 2017 implemented one of the most comprehensive pieces of bail reform legislation to date. The goal of the project is to provide advocates, practitioners, and policy makers across the U.S. with evidence about the community health effects of eliminating cash bail in order to equitably reduce pretrial detention in New Jersey and beyond.

Research Questions:

(1) Did community health improve, worsen, or remain unchanged after New Jersey’s 2017 bail reform policy, compared to control states? Were improvements equal for Black and white residents?

(2) Does structural racism or the existing social service environment moderate the health effects of bail reform?

This project is supported by an Evidence for Action Grant from the Robert Wood Johnson Foundation.


Jahn, Jaquelyn L., Jessica T. Simes, and Jonathan Jay. "Cash Bail Reform Did Not Increase Firearm Violence." Working Paper.

Pennsylvania Solitary Study (PASS)

Solitary confinement is an extreme form of prison custody involving isolation from the prison’s general population and highly restricted access to visitation and phone calls, programs, and free movement outside of a prison cell. I am co-Principal Investigator (PI: Bruce Western) of the Pennsylvania Solitary Study (PASS). PASS examines the effects and conditions of solitary confinement with a longitudinal survey of incarcerated men (N=117, including a main sample of 99 and a pretest sample of 18) who were living in a Restricted Housing Unit in the Pennsylvania state prison system during 2017. Combining fieldwork and interviews with incarcerated people and prison staff (N=22), a neurocognitive battery administered to incarcerated respondents, and an analysis of administrative records, PASS breaks new ground in research on prisons and inequality, using mixed methods to study conditions of prison confinement and effects on health and well-being, labor force participation after prison release, and recidivism. This project examines the demographic prevalence of solitary confinement. In one study, we find that 11 percent of Black men born in 1986-1989 will experience solitary confinement by age 32

This research has been supported by grants from the National Science Foundation, Robert Wood Johnson Foundation, and Arnold Ventures.


Simes, Jessica T., Bruce Western, and Angela Lee. 2022. "Mental Health Disparities in Solitary Confinement." Criminology.

Western, Bruce, Jessica T. Simes, and Kendra Bradner. 2022. "Solitary Confinement and Institutional Harm." Incarceration.

Jahn, Jaquelyn L., Nicolette Bardele, Jessica T. Simes, and Bruce Western. 2022. "Clustering of Health Burdens in Solitary Confinement: A Mixed-Methods Approach." Social Science & Medicine--Qualitative Research in Health.

Pullen-Blasnik, Hannah, Jessica T. Simes, and Bruce Western. 2021. "The Population Prevalence of Solitary Confinement." Science Advances. (Lead article)

Policing Race and Place during a Pandemic: A Multi-City Study

I am co-Principal Investigator (co-PI Jaquelyn Jahn) of a project that examines policing during the COVID-19 pandemic and how disparities in enforcement may have widened across urban neighborhoods and cities. Using a novel dataset of police contact derived from publicly available reports in cities across the United States, we analyze the extent to which policing was used to enforce social distancing and in which census tracts and cities. We therefore study two social phenomena: (1) citizens reporting crime to police by calling 911, especially to report nuisances or disturbances, and (2) police arrests. Each of these describe different pathways that could drive disparity in police contact, and both are reported by cities at the longitude/latitude on a weekly or monthly basis. Thus, our research aims to address the following questions:

(1) Aim 1: Did police contact (i.e. arrests and 911 calls regarding disturbances, curfew violations, and gatherings) in metropolitan cities change during stay-home orders and the pandemic overall, relative to the year prior?

(2) Aim 2: What is the racial disparity in rates of police contact? Did these rates widen relative to those the year prior? Are these trends stronger in cities with larger police forces before the pandemic?

(3) Aim 3: Are rates and/or racial disparities in police contact higher in areas that had higher levels of household poverty or income inequality; higher proportions of Black, Latino, or Asian residents; are more segregated; or more residents with elevated risk of SARS-Cov-2 exposure?

This research has been supported by grants from the Social Science Research Council, the Scholars Strategy Network, and the Boston University Initiative on Cities.


Jahn*, Jaquelyn L., Jessica T. Simes*, Tori L. Cowger, and Brigette A. Davis. 2022. "Racial Disparities in Neighborhood Arrest Rates During the COVID-19 Pandemic." Journal of Urban Health.
*Shared first co-authorship

Simes, Jessica T., Tori L. Cowger, and Jaquelyn L. Jahn. "School Closures Significantly Reduced Arrests of Black and Latinx Urban Youth." PLoS ONE.

Does Health Policy Prevent Exposure to the Criminal Justice System?

Although research has demonstrated the expansive role of police and carceral institutions to respond a broad range of social problems and health emergencies, existing research has not explored the capacity for health policy to influence rates of arrest or incarceration in the population. To fill this gap, I examine with Jaquelyn Jahn the potential effect of Medicaid expansion under the Affordable Care Act (ACA) on arrests in 3,035 U.S. counties. We compare county-level arrests using FBI Uniform Crime Reporting (UCR) Program Data before and after Medicaid expansion in 2014–2016, relative to counties in non-expansion states. We use difference-in-differences (DID) models to estimate the change in arrests following Medicaid expansion for overall arrests, and arrests for violent, drug, and low-level offenses. Police arrests significantly declined following the expansion of Medicaid under the ACA. Medicaid expansion produced a 20-32% negative difference in overall arrests rates in the first three years. We observe the largest negative differences for drug arrests: we find a 25-41% negative difference in drug arrests in the three years following Medicaid expansion, compared to non-expansion counties. We observe a 19–29% negative difference in arrests for violence in the three years after Medicaid expansion, and a decrease in low-level arrests between 24–28% in expansion counties compared to non-expansion counties. Our main results for drug arrests are robust to multiple sensitivity analyses, including a state-level model.


Simes, Jessica T. and Jaquelyn L. Jahn. 2022. "The Consequences of Medicaid Expansion under the Affordable Care Act for Police Arrests." PLoS ONE.