When the police arrived at Creekside Elementary School in Milledgeville, Georgia, in 2012, they found Salecia Johnson crying and flailing on the floor of her principal’s office. The principal said she was inconsolable, had thrown various items, and had damaged school property during a tantrum. Salecia was handcuffed and transported to a police station. She was 6 years old.

The arrest enraged her parents and community members, who wondered how an institution of learning could call the police on a kindergartner. But overall, black students of all genders are disproportionately disciplined in school — though they actually do not misbehave more than their peers. Researchers have found that excessive suspensions and expulsions lead to various negative outcomes for students, including dropping out of school — and studies have shown that high school dropouts are more likely to be incarcerated than those who graduate high school.

Over the past 20 years, advocates, students, educators, and researchers have coined the term “school-to-prison pipeline” (STPP) to describe how harsh school disciplinary policies and law enforcement policies intersect to feed young people into the criminal punishment system. This is part of a national trend that criminalizes rather than educates students — and one that disproportionately targets black students — as “tough-on-crime” policy has resulted in millions of mostly black and brown people winding up behind bars. Nationally, since 1990, spending on prisons has increased three times as quickly as spending on education.

Over the past 15 years, black girls have been increasingly subjected to harsh disciplinary policies, including excessive suspensions, expulsions, and arrests that push them out of school. In September, the Black Women’s Justice Institute released a report, based on U.S. Department of Education data from 2013–14, that found black girls were more than six times more likely than white girls to receive an out-of-school suspension. Though black girls made up only 16% of female students in U.S. public schools, they made up 43% of girls who were referred to law enforcement and 38% of those arrested.

The 2015 report “Black Girls Matter: Pushed Out, Overpoliced and Underprotected” presented Department of Education data that showed while black boys were suspended three times more often than white boys for the 2011–12 school year, black girls were suspended six times more than white girls. In other words, black girls were more disproportionately targeted by harsh disciplinary policies than were black boys.

Cops in schools (sometimes called "school resource officers") play a critical role in this pipeline. Since the 1950s, some U.S. schools have had on-site police, and as late as 1975, only one percent of U.S. schools reported having police officers. But by the late 1990s, most urban schools had cops. In fact, New York City public schools currently boast a force of 5,200 school resource officers (including 200 uniformed police officers) — meaning schools in NYC employ more cops than counselors. Many schools also have metal detectors and surveillance cameras under the pretext of keeping students safe.

The presence of police officers in schools often leads to harsher, sometimes brutal treatment of the students within. According to a 2011 report from the Justice Policy Institute, “when schools have law enforcement on site, students are more likely to be arrested by police instead of discipline being handled by school officials. This leads to more kids being funneled into the juvenile justice system, which is both expensive and associated with a host of negative impacts on youth.”