Authorities soon identified two suspects — 26-year-old Tamerlan Tsarnaev, who died in a shootout with police, and his brother, Dzhokhar, 20, who faces multiple charges, including 17 that carry a possible death penalty. Though jolted by the bombings and a subsequent lockdown, the city rallied under the slogan "Boston Strong."
Changing of the guard in Vatican
Pope Benedict XVI stunned Catholics around the world with his announcement in February that he would resign. The cardinal elected to succeed him, soon known as Pope Francis, proceeded to captivate many Catholics and non-Catholics alike with a new tone of openness, modesty and tolerance.
Without challenging core church doctrine, he suggested it was time to rethink policy on divorce, focus more on serving the poor, and devote less rhetoric to condemnations of gay marriage and abortion.
A Congress divided
Opinion polls showed Congress with historically low approval ratings, and the key reason was seemingly intractable partisan conflict.
Among the consequences were the harsh automatic spending curbs known as sequestration, the partial shutdown of the government in October, and bitterness in Senate after the Democrats used their majority to reduce the Republicans' ability to stall presidential nominations via filibusters.
NSA in the spying business
The ripple effect continues, seven months after the world learned of Edward Snowden. The former NSA analyst leaked vast troves of secret documents detailing NSA surveillance operations, including programs that collected Americans' phone records and eavesdropped on allied leaders.
After a stay in Hong Kong, Snowden spent a month in Moscow's airport before obtaining asylum in Russia. The leaks have roiled diplomacy, triggered lawsuits and calls for reform, and prompted warnings that terrorists could benefit from the disclosures.
Marriage equality for all
Capping decades of activism, the gay-rights movement won a monumental victory in June in the form of two Supreme Court decisions. One cleared the way for ending a ban on same-sex marriages in California, the most populous state.