1. 20 children, 6 adults gunned down at Conn. school
Armed with a high-powered rifle, 20-year-old Adam Lanza forced his way into Sandy Hook Elementary School in Newtown, Conn., and shot dead 20 children — all ages 6 and 7 — and six staff members in the second-worst school massacre in U.S. history. Sadly, it was only one of several mass shootings in 2012, including the killing of 12 people at a movie theater in Aurora, Colo. After the Newtown tragedy, President Obama and many others, including some staunch gun-rights supporters, said it was time to find ways to rein in gun violence.
2. Obama wins re-election; Democrats gain ground
Mitt Romney outcampaigned an eclectic field of Republican rivals, and bested President Obama in their opening head-to-head debate. But on Election Day, thanks in part to a vigorous get-out-the-vote operation, Obama won a second term with a large lead in electoral votes and a solid advantage in popular votes. The GOP hung on to its majority in the House, but lost two seats to remain a minority in the Senate despite early-campaign projections of gains there.
3. Drought devastates Midwest, superstorm slams East Coast
This past year's weather was deadly, costly and record-breaking. A prolonged drought stretched across the nation's heartland and devastated the region's crops and farms. Then Hurricane Sandy, which killed more than 70 people in the Caribbean, slammed into more than 800 miles of the eastern U.S. seaboard, killing at least 125 more people, and causing damage calculated at well over $60 billion — the second-costliest storm in U.S. history. Several hundred thousand homes and businesses were damaged or destroyed.
4. Supreme Court upholds Obama's health care law
By a 5-4 margin, the Supreme Court upheld the core elements of Obama's much-debated health care overhaul, which even he embraced as "Obamacare." To widespread surprise, the decisive vote came from John Roberts, the generally conservative-leaning chief justice appointed by Republican George H.W. Bush. Romney, as GOP presidential nominee, vowed to repeal the law if he won, but Obama's victory ensured the plan would proceed, with complex ramifications for insurers, employers, health care providers and state governments.
5. U.S. ambassador to Libya killed in attack
Even amid yearlong turmoil in Libya, it was a jarring incident — a Sept. 11 assault in Benghazi, widely blamed on a group with suspected links to al-Qaida, that killed U.S. Ambassador Chris Stevens and three other Americans. The U.S. ambassador to the United Nations, Susan Rice, later bowed out of consideration to be the next secretary of state because of her assertions in TV interviews that a spontaneous demonstration over an anti-Muslim video triggered the attack.
6. Penn State scandal: Paterno dies, Sandusky convicted
It was a daunting year for Penn State and its storied football program. In January, longtime coach Joe Paterno died, his legacy tarnished by the sex-abuse scandal involving his former assistant, Jerry Sandusky. In June, after a wrenching trial, Sandusky was convicted of sexually abusing 10 boys, and was later sentenced to 30 to 60 years in prison. In July, the NCAA imposed severe sanctions, including $60 million in fines, a four-year postseason ban on football and a reduction in football scholarships.
7. Economy improves, but wariness lingers over taxes, deficit
By many measures, the economy was on a welcome upswing. The unemployment rate dipped to a four-year-low of 7.7 percent, stock markets rose, builders broke ground on more homes, and November was the best sales month in nearly five years for U.S. automakers. But overshadowing the good news was deep anxiety about the economic consequences if Obama and the Democrats failed to reach a tax-and-spending deal with the Republicans.
8. Democrats, Republicans locked in 'fiscal cliff' standoff
Obama and Republican House Speaker John Boehner engaged in high-stakes negotiations over a deal to avert the so-called "fiscal cliff" that would trigger automatic tax hikes and spending cuts. The leaders narrowed some differences on Social Security and tax rates for the wealthy, but faced intense pressure from their bases to resist certain compromises.
9. Obama backs gay marriage; 3 states vote to legalize it
For supporters of same-sex marriage, it was a year of milestones. Obama, after a drawn-out process of "evolving," said in May he supported the right of gay couples to wed. On Election Day, Maine, Maryland and Washington became the first states to legalize gay marriage via popular vote. And on Dec. 7 the Supreme Court agreed to hear two cases that could further expand same-sex marriage rights.
10. Syria wracked by civil war as rebels try to topple Assad
What began in 2011 as an outbreak of peaceful protests escalated into full-scale civil war pitting the beleaguered regime of Bashar Assad against a disparate but increasingly potent rebel opposition. The overall death toll climbed past 40,000, as the rebels made inroads toward Assad's bastion of Damascus. The U.S. and many other nations were supporting the opposition, albeit wary of outcomes that might help Islamic extremists gain power in the region.