In the past, Los Angeles was a dangerous city fraught with gang wars. Lately, though, LA has become a safer city due to six changes enforced by the police cracking down on public violence and gangs.

Chicago is curbing homicides through an anti-violence initiative that uses social networks to rank people’s likelihood of killing and being killed. Police then do home visits and have personal conversations with people of high risk to inform them of consequences of future crimes.

Hawaii is one of the states with strongest gun laws and lowest gun death rates. A study found that states with stricter gun control laws, ammo regulation, background checks, and reporting of lost firearms had the lowest injury rates.

Colombia has attempted to decrease murder and homicide rates by setting up curfews for teenagers, forcing bars to close earlier in the evening, and creating gun laws to prevent the carrying of weapons. As a result of this epidemiological, data-driven approach, along with other governmental factors, the homicide rate has decreased significantly in most of the cities in which it was implemented.

Richmond, California ranked among the highest homicide rates in the country. The city created the Office of Neighborhood Safety to engage the community in the effort to curb gun violence and prevent homicides. ONS works directly with the young people who are at risk and have succeeded in reducing the homicide rate.

Palm Beach County, Florida has many of the same social problems that Philadelphia has, including “gangs, drugs, and poverty.” However, their school system has managed to keep students safe by employing “safe-school case managers” who build relationships with students, and they offer a youth court that is a system run by students who peer-review cases of unrest. The initiatives in this county has prevented school violence from happening without metal detectors and just two police officers.

Crushing poverty and extreme violence - fueled by drug trafficking and police corruption - are behind a mass migration of Central American children to the United States in recent months that has overwhelmed U.S. border resources and driven illegal immigration to the fore in U.S. congressional elections. But the United Nations has praised Nicaragua's security model, which includes social services to help youths in gangs find jobs as well as sport programs like little-league baseball teams.

A program in Philadelphia is pioneering new ways to treat the urban wounded. By seeing it as PTSD, and not pointing fingers, the city is using mental health tools to decrease violence and heal communities.

In Brooklyn's Crown Heights neighborhood, an organization called Save Our Streets Crown Heights (S.O.S.) is taking steps to disrupt violence. The organization is modeled after Chicago's violence interrupters, which employ people from the neighborhood to connect with those most at-risk and disrupt conflicts and retalitory violence.

Researchers set out to measure the efficacy of a program called Becoming a Man, which seems to be proving that, for all the billions of dollars spent on complicated anti-crime programs, something as simple and cheap as Cognitive Behavioral Therapy seems more effective in reducing crime (and, not unrelated, keeping teenagers in school).