In 2010 heavy digging was underway at the site of the world trade center. The area had once been a harbor and then a landfill. In the late 18th century, the area was filled in to extend the shoreline further into the Hudson River, expanding New York’s port and the shipping and trade opportunities that went with it.

Construction crews had been finding a variety of items including ceramic dishes, shoes, animal bones and bottles. Then, on the morning of July 13, they found a ship. Environmental and planning consultant Molly McDonald was there for the discovery.

It was 6:00 a.m. and I had just arrived on the site to oversee the demolition of a nineteenth-century wooden dock. A few minutes later, I saw two small curved timbers sticking out of the mud and said to Michael Pappalardo, the principal investigator at the site, ‘It has to be a ship.'” said McDonald to Archeology Today in 2010.

The hull was rapidly excavated piece by piece from the soft, muddy excavation area before exposure to air caused further damage to the remains. They were shipped to the Maryland Archeological Conservation Laboratory, where they were kept wet to prevent cracking and warping of the wood.

For the four years since then, the ship’s story remained a mystery but now clues are beginning to emerge. One of the first clues was the presence of burrowing holes from shipworms which are only presence in warm water with high salt levels. This indicates that, at some point, the ship sailed in the Caribbean.

Thanks to the work of Dario Martin-Benito, a postdoctoral fellow at the Swiss Federal Institute of Technology in Zurich and his colleagues we now also know when and where the ship was built.

The ships keel was found to contain hickory, which grows only in the eastern United States, which helped researchers narrow things down. Next samples of the ships timbers were compared to other samples of the wood in a search for a tree ring match.

In an article published this month in the journal Tree-Ring Research, Martin-Benito states that the wood came from the Philadelphia area, in or around the year 1773. It was constructed using the same white oak used to build Independence Hall, where the Declaration of Independence and US Constitution were signed.

“We could see that at that time in Philadelphia, there were still a lot of old-growth forests, and [they were] being logged for shipbuilding and building Independence Hall. Philadelphia was one of the most — if not the most — important shipbuilding cities in the U.S. at the time. And they had plenty of wood so it made lots of sense that the wood could come from there,” said Martin-Benito to Live Science.

At the time the ship was submerged, New York was a very different place. It was, primarily, a harbor with a population of about 20,000. It is possible that, now that the ships origins have been traced, historians may be able to provide more clues. It is still not know, for example, if the ship sank or was submerged deliberately when the harbor was filled in.