NEW YORK | Americans are commemorating 9/11 with mournful ceremonies, volunteering, appeals to “never forget” and rising attention to the terror attacks’ extended toll on responders.

A crowd of victims’ relatives is expected at ground zero today, while President Donald Trump is scheduled to join an observance at the Pentagon. Vice President Mike Pence is to speak at the third attack site, near Shanksville, Pennsylvania.

Former President George W. Bush, the commander-in-chief at the time of the 2001 attacks, is due at an afternoon wreath-laying at the Pentagon.

Eighteen years after the deadliest terrorist attack on American soil, the nation is still grappling with the aftermath at ground zero, in Congress and beyond. The attacks’ aftermath is visible from airport security checkpoints to Afghanistan. A rocket exploded at the U.S. embassy as the anniversary began in Afghanistan, where a post-9/11 invasion has become America’s longest war.

The anniversary ceremonies center on remembering the nearly 3,000 people killed when hijacked planes rammed into the trade center, the Pentagon and a field near Shanksville on Sept. 11, 2001. All those victims’ names are read aloud at the ground zero ceremony, where moments of silence and tolling bells mark the moments when the aircraft crashed and the trade center’s twin towers fell.