The President, Mrs McAleese, laid a wreath at Ground Zero in lower Manhattan yesterday on behalf of the people of Ireland.
Visibly moved, Mrs McAleese stood silently for a minute. After the brief ceremony, the President inscribed her thoughts on a makeshift memorial wall dedicated to non-Americans killed during the September 11th attack on the World Trade Centre.
"God bless those whose good hearts keep vigil here," Mrs McAleese wrote. "May the souls of the dead rest well."
The President was surrounded by New York police officers, firefighters and construction workers during her visit to the observation platform at the south west corner of Ground Zero.
The wreath of flowers in the colours of the Irish tricolour included a card signed by Mrs McAleese.
The card included a dedication to the victims "and the many who inspired us with their selfless and courageous acts." It was signed by the President "on behalf of the people of Ireland." Mrs McAleese, who was accompanied by her husband, Dr Martin McAleese, and their daughter, Emma, was assisted in the wreath-laying by representatives of two police forces, Chief Supt John O'Brien of the Garda Síochána and Insp Ronald Wasson of the New York Police Department Emergency Service Unit, which lost 14 members on 9/11.
The wall of names also proved to be particularly poignant for RTÉ reporter Tommy Gorman who is covering the presidential visit to New York.
The name of his cousin, Sligo-born Kieran Gorman, was among the list of the dead.
As she left Ground Zero, the President stopped to talk with police and firefighters, many of them Irish American. She also signed her name on a number of hard-hats offered by construction workers.
The President, who was escorted by NYPD Deputy Commissioner Michael Collins, then walked a short distance from Ground Zero to the site of the New York Police Department's permanent memorial to dead officers.
At this spot, she was presented with an Irish Tricolour which had recently been uncovered from the ruins of the trade centre. The flag was presented by Officer Brian Hanberry whose mother came to New York from Derry and whose father came from Galway.
Mrs McAleese also met Mrs Ann McCabe, widow of murdered Det Garda Jerry McCabe. Mrs McCabe is in New York to attend the annual presentation of a fellowship named in her husband's honour by the John Jay College of Criminal Justice in Manhattan.