Twenty years ago, when I started my teaching and research in gun violence prevention policy, the murder rate in the U.S. was roughly double than what it is today.

While it's difficult to pinpoint why and many theories exist, it's safe to say that homicide rates have decreased as a result of demographic changes, law enforcement strategies focused on gun offenders and illegal gun carrying, and the waning of the crack cocaine epidemic.

This sharp decline in homicides will likely surprise many, as we are inundated with stories involving gun violence. And it's true- the rate of gun violence in the U.S. is still unacceptably high. When you compare the United States to other high-income countries on most measures of violence, we're in the middle. But we're a huge outlier when it comes to lethal violence: the U.S. has the highest rate of firearm homicides among high-income countries, nearly 20 times higher than the average.

But as we see with trends in violent crime, it's possible to make progress on problems which can feel insurmountable. Today, during a Grand Rounds talk I will give at Drexel University at 4:30 p.m., I plan to outline some steps we should take to dramatically reduce gun violence in the U.S. over the long term.

First and foremost, we need to make it more difficult for people who are at high-risk of committing gun violence from accessing guns. This is a two-prong strategy: First, we must close the existing gaps in our laws and law enforcement practices which allow dangerous people from possessing guns.

Under Federal law, convictions for felonies or misdemeanor domestic battery, being subject to a restraining order for domestic violence, and a few other conditions prohibit an individual from purchasing or possessing firearms. Prospective firearm purchasers must pass a background check verifying that they meet all eligibility requirements if the seller is a federally licensed firearm dealer. But prohibited persons or anyone who does not want records linking themselves to a gun can acquire firearms from unlicensed private sellers who have no legal obligation to verify that the prospective purchaser can legally possess a firearm.

Second, we need stricter standards for legal gun ownership than what are currently mandated under Federal law. A recently published review article I wrote with Dr. Garen Wintemute found several examples in which states saw reductions in violence after tightening standards for legal gun ownership. Based on available research, a consortium of researchers have called for laws that extend firearm prohibitions to include people subject to temporary domestic violence restraining orders and people who have been convicted for misdemeanor crimes involving violence.

Public support for these approaches is quite high: A public opinion poll I conducted in 2013 found support for background checks for virtually all firearms sales is very wide – 90% overall and 82% among gun owners. We found strong support to toughen prohibitions, too: 81% overall and 76% of gun owners support prohibiting a person convicted of violating a domestic-violence restraining order from having a gun for ten years, and 83% of people overall and 80% of gun owners favor prohibiting a person convicted of a serious crime as a juvenile from having a gun for ten years.

Other approaches Philadelphia is embracing are important, too. For example, the District Attorney's office is doing excellent work prosecuting straw purchasers – those who buy guns for prohibited persons – and publicizing these actions to deter such crimes. Research shows that crackdowns on people selling guns illegally reduce the diversion of guns to criminals.

There has been much-needed attention recently on police use of deadly force under questionable circumstances throughout the nation and in Philadelphia. But police can have a profoundly positive impact by reducing gun violence in neighborhoods where shootings are a regular part of life.

Philadelphia police and researchers from Temple University collaborated on a rigorous study of police tactics to combat violent crime. The study demonstrated that special units of detectives deployed to target the highest risk offenders in hot spots for violence reduced violent felonies in those areas by 50 percent.

Police Chief Charles Ramsey has been an outspoken leader for reforms to gun policy, and has championed the use of community programs which employ violence interrupters to break the cycle of violence. My own research on the Safe Streets program in Baltimore (similar to programs in Philadelphia) found evidence that these programs can reduce shootings and save lives.

Pennsylvania Senator and gun owner Pat Toomey was an A-rated NRA member when he proposed a bipartisan deal to extend background checks. He talked about the common ground gun owners and non-gun owners share in wanting to keep guns out of the hands of those at high-risk for committing violence without infringing on the Second Amendment. We need more leaders and gun owners to demand these kinds of reforms. Our current system which benefits criminals and those who make and sell firearms does not reflect the values or wishes of the vast majority of Americans.

Read more about The Public's Health.