After years of mass shootings, the US is still trying to understand gun violence. Why?

Nearly two decades ago Congress imposed restrictions on gun violence research, and the effects are still reverberating

After every mass shooting the same questions seem to arise: how did the shooter get their gun? What were the warning signs? What's the relationship between domestic violence and white supremacist ideology and mass killings? How can we stop this from happening again?

What few people ask, however, is why, after decades of high-profile mass shootings and nearly 50,000 gun-related deaths each year, we're still trying to understand the causes of gun violence. Were it not for a nearly two-decade stoppage in federally funded gun violence research, we may have been closer to having these answers, says Garen Wintemute, an emergency room physician and longtime gun violence researcher.