And in southwestern Pennsylvania, about 1,000 people attended a memorial service in the field where Flight 93 crashed after it was hijacked by terrorists.
Other memorials planned Sunday included a Port Authority of New York and New Jersey service for the 84 employees it lost on September 11. Firefighters planned to roll out their trucks and other equipment in front of their firehouses.
Parents and grandparents read the victims' names at ground zero last year, while children's voices were heard in 2003. A selection of politicians, relatives and others read the names on the first anniversary.
Two light beams inspired by the twin towers were to shoot skyward Sunday night in an echo of the towers' silhouette. The "Tribute in Light" will fade away at dawn on Monday.