The parade yesterday through lower Manhattan also commemorated 99 officers who died of illnesses after participating in the rescue and recovery operation.
Thirty-seven members of a port agency's police department also died in the attack.
Police departments from around the United States and Canada joined the procession.
Bagpipers led marchers around the southern tip of Manhattan, ending near a memorial wall engraved with the names of the fallen NYPD officers.
The main September 11 memorial ceremony will take place tomorrow.
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