Advocates for gay marriage, marijuana legalization and abortion rights also all have made significant recent strides. Each has pushed legislation in states with friendly political environments while also taking advantage of the country's changing mindset.
Consider that in the last election:
—Washington, Maryland and Maine became the first states ever to approve same-sex marriage by popular vote. Now nine states and the District of Columbia recognize gay unions.
—Washington state and Colorado voted to legalize recreational marijuana use, and Obama's administration signaled it wouldn't pursue those users, even though the drug is illegal under federal law.
—Several Republicans who took rigid stands against abortion rights lost. Among them: GOP presidential nominee Mitt Romney.
Then, only six weeks after the election, came Sandy Hook. And gun control jumped to the front of the national conversation.
In the days and weeks before, lawmakers in the GOP-led states of Alabama, Tennessee, South Carolina and Pennsylvania considered proposals to loosen restrictions on employees keeping guns in their vehicles on work property, and Ohio's legislature passed a law allowing guns to be left in parked vehicles underneath the Statehouse.
A federal appeals court in Illinois struck down a ban on carrying concealed weapons, while Florida's GOP-led administration announced that 1 million people would soon have valid permits to carry them. Michigan's legislature also approved laws easing restrictions, though its Republican governor, Rick Snyder, later vetoed a measure allowing certain gun owners to carry concealed weapons in public places.
Public opinion polling has illustrated the trend since 2000, with more Americans now generally favoring the right to own guns over increased limitations on ownership. But there is also widespread support in surveys for reinstating the federal assault weapons ban and for limiting high-capacity magazines.
It is, for sure, a contradictory series of messages — unsurprising for an issue that asks such an intricate question: In a world of weaponry unimaginable to the people who came up with the Second Amendment, how do you strike the right balance between the individual's right to bear arms and the government's role in protecting the public?
With the latest eruption of the gun debate, we've returned to the enduring fight over libertarian principles that we've kept going for more than 200 years — the core tension between what's right for one of us and what's right for all of us.
Whatever happens with gun control in the aftermath of Newtown, the debate reveals what this generation faces as it tries to shape the nation it inherits: the enduring struggle to understand that delicate constitutional space that exists between my right to swing my arm around freely and your right not to be hit in the face.
EDITOR'S NOTE — Liz Sidoti is the national politics editor for The Associated Press.