Six months ago, Americans reacted with horror to the slaughter of 20 children and six school employees at Sandy Hook Elementary School in Newtown, Conn. Suddenly, gun safety legislation was front and center everywhere, including Washington.

Then in April, a recalcitrant Senate succumbed to pressure from gun manufacturers and the National Rifle Association's leadership and failed to pass even the most modest measure, a bill to extend background checks to gun shows and Internet sales. The president was angry, the families of victims frustrated, and the moment for gun control seemed lost.

But the Senate vote was hardly the whole story. Since the Newtown tragedy, gun regulation has made enormous gains in states across the country, with more on the horizon. In fact, an unprecedented number of gun control laws have been introduced, debated, voted on and enacted this year. What a difference Sandy Hook and six months have made.

Since December, six states have strengthened firearms laws. Connecticut, Maryland and New York passed packages that include laws to expand and improve background checks, limit the sale or transfer of military-style assault weapons and large-capacity ammunition magazines, require safety training and improve systems for keeping guns away from domestic violence abusers and the dangerously mentally ill. Delaware and Colorado passed laws requiring background checks on all gun sales, the very requirement that our federal government failed to enact. California added enforcement teeth to its law to confiscate guns from criminals and the mentally ill.

There have been setbacks: In Nevada a background-check bill was vetoed by the governor. But failure this year doesn't mean the fight is over. In at least four other states where such legislation didn't become law, advocates are gearing up for another try. In all, we've seen a year-to-year increase of 231 percent in the introduction of common sense gun-safety legislation nationwide.

Post-Newtown success isn't just about passing effective new legislation; it includes the defeat of several dangerous bills in some surprising places. The governors of two traditionally red states, Utah and Montana, vetoed legislation that would have allowed weapons to be carried in public without any permit or background check. The gun lobby argues that such laws deter gun violence, but in these two states, the governors paid attention to research that shows more unregulated guns in public places puts communities at greater risk of gun violence. In Georgia, a bill that would have allowed guns in courthouses, churches and college campuses was defeated, and in Wyoming, a bill authorizing teachers to carry guns in schools failed to pass.

One reason for these successes is new energy brought to the cause from average Americans. Many grass-roots groups have emerged since Newtown, including Moms Demand Action, Newtown Action Alliance and Americans for Responsible Solutions (started by former Arizona Rep. Gabby Giffords and Mark Kelly). And many powerful existing groups have chosen to focus for the first time on this issue, including MoveOn, Credo and the Center for American Progress.

Well-respected research underlines what Americans instinctively get: Strong laws that keep guns out of the wrong hands reduce violence. More than 90 percent of Americans support universal background checks, including more than 80 percent of gun owners and more than 70 percent of NRA members. In the 20 years since a shooter with an assault weapon left eight dead and six wounded in San Francisco (and inspired the formation of our organization, the Law Center to Prevent Gun Violence), the California Legislature has passed more than 30 laws to protect our communities and seen the state's rate of gun death decline by 56 percent.

Those 20 years provide us with a long view regarding the defeat in the Senate in April. That bill didn't pass but it was, in its way, a victory. The fact that it was introduced, that hearings were held, and that it got 55 votes represents progress. After the vote, several senators felt real repercussions from their decision to vote against the bill, including Sen. Kelly Ayotte, R-N.H., whose approval rating dropped by more than 15 percent immediately after the background check vote. There are now real consequences for legislators who choose not to represent the will of their constituents on this issue.

Gun violence is not a problem without solutions. We know what works, and we are finally seeing smart gun laws adopted in other states.

Americans woke up to the personal toll of gun violence in a dramatic way six months ago. And states are now answering the call to put safety first.

Robyn Thomas is the executive director and Juliet Leftwich is the legal director of the Law Center to Prevent Gun Violence. They wrote this for the Los Angeles Times.