The United States and the world have changed significantly in the dozen years since terrorists hijacked jetliners and launched the biggest attack on American soil since Pearl Harbor. Here are 10 of those changes.
2. Bin Laden is gone. It took more than nine years, but the United States found and killed the al-Qaida leader who bankrolled the 9/11 attacks. While terrorism threats remain, they do not have at their root a person such as bin Laden who personified the anti-U.S. movement.
4. The Arab spring. Anti-authoritarian ferment in the Middle East Tunisia, Libya, Egypt all toppled longtime military-backed leaders, and Egypt saw a military coup against the successor government. Rebels and protesters have risen up in Syria, Yemen and Bahrain as well, with mixed results.
5. What Google has wrought. Hand in hand with that tumult has been the exploding use of Twitter, G-chat, Facebook and similar services in tightly controlled societies worldwide, all giving voice to people who are denied printing presses and broadcast licenses. Thousands have followed protests in Iran and Egypt -- and videos from Syria -- through social networks. The pattern has repeated itself across the globe, from China to Brazil.
6. Rise (and fall) in U.S. fervor for military action. After the 2001 attacks, the Bush administration moved quickly into Afghanistan in the hunt for Osama bin Laden and the fight against the Taliban. Claiming a link to weapons of mass destruction, it committed the Pentagon to Iraq. The two long wars have sapped America's appetite for military action, reflected in polls showing nearly two-thirds of Americans oppose even limited military efforts in Syria.
8. Emergence of a multicultural U.S. mainstream. In 2012, whites made up the lowest percentage of the U.S. population in American history. Census data showed more whites died than were born, a slump more than a decade before the predicted decline of America's white population. The fastest growing group is multiracial Americans. The demographic shifts have buoyed Obama and Democrats, who have outsized support among women and gays and lesbians as well.
9. "We're broke." The last U.S. budget surplus was in fiscal year 2001. The national debt now is more than $16.7 trillion -- or about $53,000 per person. Rising health and defense spending played a big role, as did a cut in the personal income tax near the start of the Bush administration. Persistent unemployment and the first waves of baby boomer retirements have also contributed to unease about the economy.
David Beard is an editor for The Washington Post.