At 14 minutes to 9 on Thursday morning, for thousands of people in New York City and across the region, time will stop and silence will descend, filled by memories of another balmy blue-sky morning two dozen years ago.

Then, on a memorial plaza near the bottom of Manhattan, survivors and relatives of the nearly 3,000 people killed in the Sept. 11 attack will begin reading the names of the dead, as New York’s most somber annual event takes place for the 24th time.

The toll from the attack continues to grow: Deaths over the years from illnesses caused by the toxic materials in the air and in the rubble at ground zero have almost certainly surpassed those on Sept. 11 itself.

Tributes to the victims and their families took place across the city this week as law enforcement groups and organizations supporting survivors prepared to mark the anniversary.

On Wednesday afternoon, at a firehouse near the World Trade Center site, firefighters gathered in front of a memorial wall to call attention to cuts to federal health programs for Sept. 11 survivors and to honor the 409 members of the Fire Department who have died of 9/11-related diseases, including 39 in the last 12 months. In the initial attack, 343 firefighters lost their lives.

“As we stand in the shadows of this beautiful monument, sometimes I feel this monument overshadows the lingering effects of what occurred after that day,” Lt. James Brosi, president of the Uniformed Fire Officers’ Association, said as he stood by the wall, which is engraved with the names of fallen firefighters.

According to the Centers for Disease Control and Prevention, more than 24,000 responders who worked at the World Trade Center site or at the debris sorting pile on Staten Island have developed cancer.

Other remembrances were more private. Valentina Lygin, 78, visited the World Trade Center plaza on Wednesday and laid a flower by the name of her son, Alexander Lygin, etched into one of the memorial pools.

Mr. Lygin was 28 when he perished in the North Tower, his mother said. He worked on the 104th floor in a computer programming job and had planned to get married that October.

Ms. Lygin recalled rushing with her husband from Brooklyn to Lower Manhattan that day and being stopped near the World Trade Center. “We just said, ‘We are here to get our son and take him home,’” she recalled. Later, his driver’s license was found in the debris.

Ms. Lygin now lives in North Carolina, but said she visited New York twice each year to honor her son: on Sept. 11 and on his birthday, Jan. 16.

“What I want is for people to remember,” she said.

Leaving the 9/11 Museum on Wednesday, Anthony Skut, a firefighter from Colchester, Conn., recalled searching for remains in debris piles in the days after the attack.

“The New York people were grieving, but they were cheering us on,” Mr. Skut, 67, said. He added: “Every year, I pay my respects.”

New York has changed, healed and rebuilt dramatically since 2001 in many ways. The population of the community district that includes Lower Manhattan has more than doubled since 2000. The city — where Islamophobia spiked after the 2001 attacks — is on the precipice of electing its first Muslim mayor: Zohran Mamdani, a state assemblyman who was a 9-year-old growing up in Manhattan when the twin towers fell.

While candidates often pause campaigning on Sept. 11 out of respect for the day, its political significance did not go unnoticed. On Tuesday, former Gov. Andrew M. Cuomo held a news conference with Sal Turturici, a firefighter who responded to the attacks and helped with recovery efforts. Mr. Turturici and his wife endorsed Mr. Cuomo for mayor and criticized Mr. Mamdani for his perceived association with the streamer Hasan Piker, who once made insensitive comments about Sept. 11 that he later disavowed. (Mr. Mamdani appeared on Mr. Piker’s show in April.)

Mr. Mamdani, who holds a commanding polling lead, plans to attend Thursday’s ceremony at the memorial plaza. So do the current mayor, Eric Adams, who is running for re-election; Mr. Cuomo, who is in second place behind Mr. Mamdani in the polls; and Curtis Sliwa, the Republican nominee.

Vice President JD Vance is also expected to attend.

The reading of the names of the dead takes hours. It is interrupted by five more moments of silence, marking the times when each plane crashed — including Flight 93 in western Pennsylvania — and each tower fell.

Anusha Bayya and Tim Balk contributed reporting.