The debate over gun control in America rages in the wake of the massacre in Tucson, which left 6 dead and 14 wounded.

The United States has seen many such massacres, including the Columbine shootings, the Virginia Tech shootings and countless more gun-related mass killings, most of which could have been prevented by stricter gun laws.

Obviously, whatever we are doing to prevent gun-violence in this country is not enough.

Consider New York City and Washington, D.C. Both cities instituted strict gun control laws with very different results.

In New York City, gun-related crimes plummeted, making it one of the safest large cities in the country.

In D.C., gun violence levels changed very little, if at all, with the new legislation. Guns remained relatively available in Washington, D.C. because the city’s close proximity to Virginia and Maryland, two states with much more lenient gun laws.

Guns used in violent crimes are often obtained in states with lax gun laws and trafficked to states where guns are more difficult to buy. It follows that if guns were impossible to purchase in any state, one’s ability to get a gun, legally or illegally, would drop significantly.

Gun control may not be perfect, but it works. There may be no way to prevent all gun violence. Even the strictest gun laws are flawed, and yes – if guns are outlawed, outlaws will still be able to get guns.

But the guns used in the biggest massacres in U.S. history, including at Virginia Tech and in Tucson, were obtained legally.

Gun control laws may not be able to stop every gun-related crime, but they very possibly could have prevented some of the worst gun crimes the world has seen.