"They are commemorating the parade to the victims of the World Trade Center," said Nicholas Estavillo, the New York Police Department's Chief of Patrol, and the parade's grand marshal.
"I was selected as representative of the officers that were lost. ... It's a tremendous honor."
Last year's celebration also drew extra police, in response to a melee after the end of the parade in 2000 in which more than 50 women were sexually accosted in and around Central Park.
No incidents were reported as the parade was underway Sunday.