PROJECT SUMMARY Suicide rates among Black youth have increased significantly in recent decades, exceeding those among Whites by over 60%. Black youth also surpass all other racial/ethnic groups in Emergency Department (ED) visits for suicidal ideation/self-harm. Scholars have suggested that racism and discrimination may be potential causes of these concerning trends. One visible and pervasive example of routine discrimination against Black populations is hyper-surveillance through racially targeted police stops. Research shows that police contact is a social determinant of mental health among youth, with an increase in psychological distress, anxiety, depression, and trauma symptoms following police contact. However, no study has examined the causal relationship between racially disproportionate police stops and ED visits for suicidal ideation/self-harm and suicide mortality among Black youth. To address this gap in research, we propose to examine the relation between police stops and (i) ED visits for suicidal ideation/self-harm and (ii) suicide mortality among Black youth (outcomes). We propose a multi-state, county-level examination of the relation between police stops of Black individuals and suicide-related outcomes (ED visits for suicidal ideation/self-harm, suicides) across 10 US states (AZ, FL, KS, MA, MN, NC, NJ, NY, SC, WI), from 2006 to 2019 using national, high quality datasets and advanced econometric methods. We also leverage the unique case of the New York Police Department's (NYPD) stop, question, and frisk (SQF) policy as a natural experiment towards causal examination of the relation between racially targeted police stops and suicide-related outcomes among Black youth in New York City (NYC). In 2013, a federal court ruled NYPD’s SQF policy unconstitutional (Floyd, et al. v. City of New York, et al., 2013), and the number of stop-and-frisks conducted by NYPD declined sharply. We will use this ruling as a natural experiment to examine the causal impact of hyper-surveillance on suicides among Black youth in New York City. We will retrieve data on police stops by race for 10 US states from the Stanford Open Policing Database, and New York City-specific police stops data from the New York Civil Liberties Union's stop-and-frisk database. Suicide mortality by region, age, race, and sex will be obtained from the National Center for Health Statistics mortality database. We will acquire ED visits data (by ICD9/10 diagnosis code, race, age, sex, county, month, year) from the State Emergency Department Database (SEDD) and the State Inpatient Database (SID). We will formulate our exposures as the volume of police stops of black persons and the ratio of Black to White police stops (per 100,000 population). We will conduct empirical analyses using (1) two-way fixed effects, (2) time series, (3) difference-in-difference, and (4) synthetic control methods to examine the spatio-temporal relation between our outcomes and exposures. Our study will ...