The precedents include the Los Angeles riots that broke out after the 1992 acquittal of police officers for beating Rodney King.
Those riots happened nearly three decades after the 1965 Watts riots, which began with Marquette Frye, an African American, being pulled over for suspected drunk driving and roughed up by the police for resisting arrest.
They located and returned enslaved people who had escaped, crushed uprisings led by enslaved people and punished enslaved workers found or believed to have violated plantation rules.
The first slave patrols arose in South Carolina in the early 1700s.
The more commonly known precursors to modern law enforcement were centralized municipal police departments that began to form in the early 19th century, beginning in Boston and soon cropping up in New York City, Albany, Chicago, Philadelphia and elsewhere.
The first police forces were overwhelmingly white, male and more focused on responding to disorder than crime.
Connie Hassett-Walker does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
Outrage over racial profiling and the killing of African Americans by police officers and vigilantes in recent years helped give rise to the Black Lives Matter movement.
As Eastern Kentucky University criminologist Gary Potter explains, officers were expected to control a “dangerous underclass” that included African Americans, immigrants and the poor.
Through the early 20th century, there were few standards for hiring or training officers.