Protests against police have broken out across the country. Here's how policing has evolved in the US since its beginnings in the 1600s.

The night watch was made up of men who volunteered for a night's worth of work. Sometimes people were put on the watch as a form of punishment for committing a crime. These watchmen, however, were known to sleep and drink while on duty.

The first night watch was founded in Boston in the 1630s and then New York followed suit in the 1650s.

During this time period, the wealthiest in the colonies also hired people for protection. Those hired for protection were mostly criminals.

The first form of policing in the South was known as slave patrol, which began in the colonies of Carolina in 1704. The patrol was usually made up of three to six men riding horseback and carrying whips, ropes, and even guns.

The group's main duties included chasing and hunting escaped slaves, releasing terror on slave communities to prevent riots, and to keep plantation owners in check, according to Ben Fountain's book, "Beautiful Country Burn Again."

The slave patrols lasted until the Civil War and eventually gave way to the Ku Klux Klan.

Immigrants from Germany and Ireland began settling in cities like Boston and New York between 1820 and 1860. This new group of immigrants clashed with original settlers from England and The Netherlands. As the original settlers argued that the new immigrants were ruining American society, crime began to rise. The cities saw mobs, public lewdness, disorderly conduct, and prostitution.

The cities were ill-equipped to keep order and the night watch was rendered useless.

Shortly after, in 1845, New York began its own force, followed by Chicago, New Orleans, and Cincinnati. By the 1880s, almost every major city in the country had a police force.

Each police department was public and bureaucratic, had full-time policemen, and reported to a governmental authority.

It wasn't until the 1850s that the cities started developing detective units whose main jobs were to investigate crimes.

At the time, America was a political machine, meaning local businesses and police forces reported to a single political leader in exchange for a reward. As Time magazine reported, this led to corrupt politicians and corrupt police officers. For example, some politicians paid off officers to ignore certain groups' illegal activities.

Allan Pinkerton was an immigrant from Scotland who created the Pinkerton National Detective Agency, which was made up of private detectives who stopped train robberies and prevented strikes.

The early 1900s marked the beginning of a new police system. August Vollmer, "the father of modern policing," stressed the importance of sociology, social work, psychology, and management in police work. In this system, officers patrolled the neighborhoods they lived in on foot. Vollmer also made sure policemen went to college and even created a separate system for juveniles to be tried and punished instead of trying them as adults.

During Prohibition, cops were tasked with stopping the sale and distribution of alcohol. At times, the police would confiscate the illegal substance and dump it into sewage drains.

At the same time, organized crime began to take shape, and protests, riots, and petty crimes were also on the rise. The local police forces could not keep up.

In response, the Department of Treasury created "T-Men," a group of 4,000 men who were charged with enforcing the laws of Prohibition. State governments also started creating their own police forces in the early 1900s to stop the spread of crime in cities.

Instead of following Vollmer's model, which concentrated on social work and psychology, Hoover made sure local forces were fighting street crimes. Under this new system, police officers were less connected to the neighborhoods they worked in as officers patrolled neighborhoods by car.

During the 1960s, African Americans began to challenge the way police were treating their communities. To protest the treatment and racial profiling, riots, boycotts, and peaceful protests broke out in the US, mainly in the South. In response, the police used harsh tactics to keep order, including tear gas, high-pressure water hoses, and attack dogs. Some of these events were televised nationally.

Policemen at the time were also profiling the LGBTQ community in cities all over the US by raiding bars and nightclubs and arresting patrons, especially at the Stonewall Inn, according to CNN.

On June 28, 1969, policemen raided the Stonewall Inn in New York City and started arresting people. In response, the patrons and neighborhood residents fought back, starting a riot that lasted six days. The fight against the police sparked the gay rights movement.

Studies, like in Kansas City, Missouri, found that patrolling police cars in neighborhoods did not help reduce crime, nor did it ease people's fears. In fact, it increased the community's dissatisfaction with police forces.

In response to these findings, some departments attempted a return to community policing. This form of policing placed minority officers in minority neighborhoods. This model also incorporated the community in helping police the neighborhood. The police officers were meant to become close and familiar with the residents in the community. This became increasingly popular in the '90s. By the early 2000s, two-thirds of police forces across the US implemented community policing policies.

In the 1990s, crime rates in the US started to decline, so that it had roughly halved by 2015. While the exact cause is not known, research cited by the Brennan Center for Justice found that hiring more police officers helped decrease crime — in fact, according to the research, up to 10 percent of the decrease in crime in the 1990s was due to hiring more police. Another theory is that technology used by police, such as their crime tracking system, improved in the 1990s, helping them recognize and address trends more effectively.

On April 20, 1999, two students opened fire at Columbine High School, killing 13 people. At the time, police responded by setting up a perimeter before going after the suspects. The response was widely criticized because of the amount of time the police took before moving into the school.

Since then, the police have listened to the critiques and transformed their response to mass shootings. Now, one to four officers rush into a mass shooting site and follow the sound of the gun to confront the shooter.

This technique has been successful in a string of US school shootings over the past few years. In fact, 75% of mass shootings since Columbine have required police to confront and shoot the suspect at the scene. Some police forces have been lauded for how they've handled active shooters, such as the Capitol Police, who were celebrated for their quick response to a shooting at a Republican congressional baseball practice in 2017.

On September 11, 2001, 2,000 NYPD and Port Authority police officers responded to the scene when two planes flew into the World Trade Center in New York City. First responders were called heroes for risking their lives and running towards danger.

The terrorist attack also affected the future of policing. The National Criminal Justice Reference Service found that departments "have evolved to include not only counterterrorism but also the adoption of an all-crimes approach, with the goal of striking a balance between criminal intelligence and intelligence related to terrorist threats." These forces created counterterrorism units that worked directly with state and federal agencies.

Immediately after 9/11, police work was emphasized and revered in some communities. Other communities, however, experienced racial profiling as a result of 9/11.

"Since September 11, our nation has engaged in a policy of institutionalized racial and ethnic profiling," US Rep. John Conyers said in 2002. "If Dr. Martin Luther King Jr. were alive today ... he would tell us we must not allow the horrific acts of terror our nation has endured to slowly and subversively destroy the foundation of our democracy."

The American Civil Liberties Union agreed with Conyers in a 2009 report.

"The practice of racial profiling by members of law enforcement at the federal, state, and local levels remains a widespread and pervasive problem throughout the United States, impacting the lives of millions of people in African American, Asian, Latino, South Asian, Arab and Muslim communities," the ACLU wrote.

Police departments also began tactics like New York City's stop-and-frisk, in which police officers stopped anyone on the street they deemed suspicious and patted the person down. But critics said the tactic was a form of racial profiling because the majority of people detained were young black and Latino men. Evidence showed that police were disproportionately targeting minorities in these cases. In 2013, the mayor announced to reform the controversial policy.

On July 17, 2014, New York police officer Daniel Pantaleo attempted to arrest Eric Garner on suspicion of selling illegal cigarettes. The officer put Garner in a chokehold and wrestled him to the ground. Garner said "I can't breathe" 11 times. He was pronounced dead at the hospital. The entire incident was caught on camera, sparking a national outcry. People all over the country highlighted the disproportionate treatment of black people in the US by the police.

It sparked protests all over the country, demanding the firing and arrest of Pantaleo. A grand jury did not indict Pantaleo, and federal authorities declined to bring civil rights charges against him.

After the death of Eric Garner and another case the same year — the shooting of Michael Brown — the public called for mandatory body cameras. The hope was that police would reduce racial profiling and could be held accountable for their actions. On the flip side, departments hoped body cams would increase transparency and help solve crimes quicker.

In 2016, almost half of the police forces in the US implemented policies that required body cameras for police officers. Only Nevada and South Carolina require all officers to wear the equipment. However, studies show that wearing a body camera does not significantly change an officer's behavior, according to Pew.

While body cameras have captured violent and contentious moments between police and civilians, they have also caught acts of community work carried out by officers. In March 2020, for example, a supervisor in Gwinnett County, Georgia, was auditing body cameras and found footage of two officers taking a birthday cake to a little girl after finding out her mom couldn't afford one.

On May 25, 2020, George Floyd was arrested on the suspicion that he used a counterfeit $20 bill in Minneapolis, Minnesota. Officer Derek Chauvin said Floyd resisted arrest. Chauvin put his knee on Floyd's neck for eight minutes as Floyd said "I can't breathe." He was unconscious when he was taken to hospital, where he was pronounced dead. Video of the incident went viral.

Chauvin has been charged with third-degree murder and manslaughter.

The protests started in Minnesota, where Floyd was killed, but unrest broke out in cities all over the US. These rage-filled protests have led to arson, looting, and violence. Some police officers have responded with tear gas, by running cruisers through crowds, and with riot guns, while others have stood in solidarity with the protesters.

As tensions rise across the country, people are demanding changes with policing in the US.

• Read more:
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• A New York police officer drew his gun on protesters. Mayor Bill de Blasio says he 'should have his gun and badge taken away.'
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