Americans are remembering 9/11 with moments of silence, readings of victims' names, volunteer work and other tributes 21 years after the deadliest terror attack on U.S. soil.
Victims' relatives and dignitaries will convene Sunday at the places where hijacked jets crashed on Sept. 11, 2001 - the World Trade Center in New York, the Pentagon and a field in Pennsylvania.
Other communities around the country are marking the day with candlelight vigils, interfaith services and other commemorations.
The observances follow a fraught milestone anniversary last year. Though this Sept. 11 may be less of an inflection point, it remains a point for reflection on the attack that killed nearly 3,000 people, spurred a U.S. "war on terror" worldwide and reconfigured national security policy.