Thousands of 9/11 victims' relatives, survivors, rescuers and others are expected to gather Monday at the World Trade Center to remember the deadliest terror attack on American soil.
Sixteen years later, the quiet rhythms of commemoration have become customs: a recitation of all the names of the dead, moments of silence and tolling bells, and two powerful light beams that shine through the night.
Yet each ceremony also takes on personal touches. Over the years, some name-readers have added messages ranging from the universal ("the things we think separate us really don't we're all part of this one Earth") to the personal ("I love you and miss you. Go Packers!").
"Thank you, New York, for continuing to honor the victims of 9/11 and the privilege of reading their names," Judy Bram Murphy added last year. She lost her husband, Brian Joseph Murphy.
Nearly 3,000 people died when hijacked planes slammed into the trade center, the Pentagon and a field near Shanksville, Pennsylvania, on September 11, 2001, hurling America into a new consciousness of the threat of global terrorism.
President Donald Trump, a native New Yorker observing the anniversary for the first time as the nation's leader, is scheduled to observe a moment of silence at about the time the first airplane hit. The White House said he is to be joined by first lady Melania Trump.
He also planned to participate in a 9/11 observance at the Pentagon. Defense Secretary Jim Mattis and Gen. Joseph Dunford, chairman of the Joint Chiefs of Staff, are hosting a private observance for victims' relatives there at 9:11 a.m.
After the names are read at that ceremony, there's a public observance, with a wreath-laying and remarks.
Vice President Mike Pence and US Secretary of the Interior Ryan Zinke are scheduled to deliver remarks at the Flight 93 National Memorial near Shanksville.
It's on the rural field where one of the airliners crashed after passengers and crew fought to wrest control away from the terrorists who'd hijacked it and were heading for Washington.