On Decemeber 14th 2012, 20 children went to school and never came home.

Twenty year-old Adam Lanza entered Sandy Hook elementary school in Newtown, Connecticut, and opened fire on children and teachers, killing 26 people in total. Prior to this, he shot and killed his mother.

Four years on, what movement has there been when it comes to reforms to the mental health system and gun control?

Empty playground swings are in place at the new Sandy Hook Elementary School, Friday, July 29, 2016, in Newtown, Conn. The school was torn down after a gunman entered it in December 2014 and killed 20 first graders and six educators. The $50 million, 86,800-square-foot replacement building opened last summer.

The future of gun control at the Trump helm 

Congress rejected bills to tighten background checks on gun sales and ban military-style “assault weapons” in April 2013.

After the Pulse nightclub shooting in Orlando this year, Democrats in Congress held a sit-in on the floor of the House of Representatives simply to demand a vote on gun control legislation. Republican House leaders refused even to allow a gun control vote.

President Barack Obama has been in office through 14 shootings, including Sandy Hook. Speaking after the incident, he urged the nation to come together and "take meaningful action to prevent more tragedies like this, regardless of the politics."

"The majority of those who died today were children - beautiful little kids between the ages of 5 and 10 years old," he said in the White House briefing room, pausing to wipe a tear from his eye. "They had their entire lives ahead of them - birthdays, graduations, weddings, kids of their own. Among the fallen were also teachers -- men and women who devoted their lives to helping our children fulfill their dreams. So our hearts are broken today."

Despite this, Obama has made little federal progress toward what he has repeatedly described as "common-sense gun laws." It is, the outgoing president has acknowledged, one of the biggest regrets of his time in the White House.

With President-elect Donald Trump's arrival to the White House imminent and Republicans controlling both houses of Congress, the NRA is getting ambitious. Trump has vowed to nominate a supreme court justice who supports gun rights.

"This is our historic moment to go on offense," NRA CEO Wayne LaPierre told members in a post-election video address, having backed Trump with $30 million in ad buys.

Trump does not support a ban on assault weapons. However, during his campaign, Trump proposed more aggressive stop-and-frisk policing with a focus on taking away people’s guns.

"If they see a person possibly with a gun or they think may have a gun, they will see the person and they’ll look and they’ll take the gun away,” Trump said Thursday on Fox News, laying out his vision of how the practice works. “They’ll stop, they’ll frisk, and they’ll take the gun away and they won’t have anything to shoot with."

"I mean, how it’s not being used in Chicago is ”• to be honest with you, it’s quite unbelievable, and you know the police, the local police, they know who has a gun who shouldn’t be having the gun. They understand that," Trump added.

Mental health

A state investigation of the shooting found that gunman Adam Lanza had not been receiving mental health care in the years before the shooting, despite prior advice from mental health professionals throughout his childhood and adolescence.

Non-profit group Sandy Hook Hope is trying to build a movement beyond the high-profile failure to enact federal gun control legislation, with an emphasis on the mental health of the perpetrator.

Obama signed a partisan health bill, submitted by Sandy Hook Hope, that includes funding to expand access to mental health care.

"This is our first big success at the federal level," said Mark Barden whose seven-year-old son Daniel was shot to death in his first-grade classroom.

Connecticut senator Chris Murphy said the bill would not have been passed without the group's advocacy.

The group also released a new public service announcement video this month focused on spotting the signs of violence.

Trump has said previously he wants violent people "off the streets", saying that shootings involving the mentally ill punish regular gun owners. 

"And why does this matter to law-abiding gun owners? Once again, because they get blamed by anti-gun politicians, gun-control groups, and the media for the acts of deranged madmen," Trump said.

He's also been unclear as to how he specifically plans to "fix" the health system regarding mental health, but has called for expanding mental-health treatment programs.

A playground bench is colorfully decorated at the new Sandy Hook Elementary School.

Crime rates

Four months after the Sandy Hook shooting, Connecticut state legislators passed a ban on new high-capacity magazines and ordered background checks on private gun sales.

Connecticut has had the second-largest decrease in violent crime by about a million incidents, or 8.5% between 2014 and 2015.

The state experienced its lowest of number of crimes since 1967 and was one of just nine states that saw a drop in violent crime over the year.

Specifically in Newtown, where Sandy Hook elementary school is based, saw a 4.24% increase per 10,000 residents and percent change between 2014 and 2015.

Painted hand prints with names of teachers and students are on a playground bench at the new Sandy Hook Elementary School in Newtown, Conn. Students attended the first day of classes there on Monday, Aug. 29, 2016. 

New York was the first to pass a wide-ranging series of increased gun control measures following the incident, which included broadening the scope of what is classified as an assault weapon and banning the sale of certain high-capacity magazines and banning the direct sale of ammunition on the internet.

New York City saw a significant drop in major crimes in the first quarter of 2016 with the fewest murders and shootings in its recorded history. Shootings decreased 14% compared with those months in 2015. 

Mayor Bill De Blasio said the statistics are linked to an increased focus from the New York City Police Department on getting guns off the streets, with NYPD seizing over 800 guns, a more than 15% increase compared with the first quarter of 2015. Gun arrests are also up by about 13 percent, de Blasio said at a press conference. 

"In the absence of action by Congress, the states are moving forward and they're leading the way," said Kristin Brown, the acting policy director for the Brady Campaign to Prevent Gun Violence. "Our thought is that eventually Congress will get the message."