A U.S. Navy ship that was built with steel from the fallen World Trade Center towers pulled into port at its namesake city Monday morning with a 21-gun salute near the site of the Sept. 11 terrorist attacks.

Emergency services workers, victims' families and members of the public crowded into a waterfront public viewing area to greet the USS New York and its crew, all of whom stood at attention.

After a pause, the sound of gunfire filled the air.

After its stop near what is known as Ground Zero, the ship travelled up the Hudson River toward the George Washington Bridge, escorted by about two dozen tugboats and other vessels.

It will head back south again to dock at Pier 88, where an official commissioning ceremony will take place on Saturday.

The bow of the US$1billion, 208-metre vessel contains 7.5 tons of steel from the fallen buildings.

"It's a transformation ... from something really twisted and ugly," Rosaleen Tallon, who lost her firefighter brother, Sean, on 9/11, told The Associated Press. "I'm proud that our military is using that steel."

According to Navy spokesperson Lt. Cmdr. Colette Murphy, 13 per cent of the 361 sailors on the ship are from New York State, a higher figure than usual. A number of Navy personnel submitted requests to serve on the vessel, Murphy said.

In addition to Navy personnel, about 250 Marines also make up the New York's crew.

The vessel will stay in the Big Apple until Veteran's Day before it makes its way to Norfolk, Va, where it will engage in training and other exercises for about a year.

The ship's flight deck can carry helicopters, as well as the MV-22 Osprey tilt-rotor aircraft.

The ship is what's known as a San Antonio-class amphibious dock vessel. There are four others in service, and four more being built, two of which are named to commemorate 9/11. The USS Arlington honours the attack on the Pentagon, while the USS Somerset pays tribute to the county in Pennsylvania where United Airlines Flight 93 crashed.

Plans for the ship were already underway before 9/11. However, a year after the attacks, the Navy announced that the ship would be named the New York to honour both the city and the state, as well as the nearly 3,000 victims of the worst terrorist attacks on U.S. soil.

With files from The Associated Press