New York City:
8:39 a.m. Eastern — Program begins at the National September 11 Memorial Plaza at the World Trade Center site, with bagpipers and drummers. The Young People’s Chorus of New York City sings the National Anthem.
8:46 a.m. — Moment of silence marking when American Airlines Flight 11 hit the north tower, and houses of worship toll their bells. Then family members will read the names of those killed.
9:03 a.m. — Moment of silence marking when United Airlines Flight 175 hit the south tower.
9:37 a.m. — Moment of silence marking when American Airlines Flight 77 hit the Pentagon.
9:59 a.m. — Moment of silence marking when the south tower fell.
10:03 a.m. — Moment of silence marking when United Airlines Flight 93 crashed near Shanksville, Pa.
10:28 a.m. — Moment of silence marking when the north tower fell.
12:30 p.m. — Program finishes with another choral performance and three trumpeters performing taps.
Sunset — The ‘‘Tribute in Light’’ art installation is turned on until dawn Wednesday.
8 p.m. — National September 11 Memorial closes.
Washington, D.C.:
President Barack Obama, first lady Michelle Obama and the White House staff mark a moment of silence on the south lawn of the White House. The president and the first lady attend a Sept. 11 memorial event at the Pentagon and visit service members at the Walter Reed National Military Medical Center in Bethesda, Md.
Defense Secretary Leon Panetta hosts remembrance ceremony at the Pentagon memorial.
Congress holds a Sept. 11 remembrance ceremony.
Shanksville, Pa.:
9:30 a.m. — Program begins at the Memorial Plaza, with keynote remarks from Vice President Joe Biden. Secretary of the Interior Ken Salazar attends.
10:03 a.m. — At the moment Flight 93 crashed, family members and community residents read the names of those lost and ring Bells of Remembrance.
Reno, Nev.:
Republican presidential candidate Mitt Romney speaks at the annual conference of the National Guard Association of the United States.