New York — It's a heart-wrenching ritual repeated every year: Family members and first responders return to ground zero to remember loved ones lost on September 11, 2001. On Wednesday, bells marked when the planes hit the Twin Towers and when the buildings fell as the names of the fallen were read.

Many children spoke about parents they never met or got to know. "Andrew, Mom and I miss you very much every day, and we know you're watching over us," one man said.

New this year at ground zero: A 9/11 memorial glade featuring stacks of granite in tribute to the first responders who became ill or died after being exposed to toxins. "We pray for all those first responders who have or will become ill as a result of their dedication and sacrifice," a woman said during the ceremony.

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Nearly 3,000 people died on this day 18 years ago, and while the neighborhood in lower Manhattan has changed so much since then — the love and sense of loss — remain the same. "So many milestones that he's missed," a woman said. "... This one's kind of hard."

In Washington, D.C., President Trump attended a ceremony to remember the people who died when a jet slammed into the Pentagon. "The first lady and I are united with you in grief," Mr. Trump said.

Near Shanksville, Pennsylvania, Vice President Mike Pence paid tribute to the passengers onboard United Flight 93. From Pennsylvania to Washington to New York the refrain was the same: Never forget.