The United States Supreme Court has settled a long-running territorial dispute between the states of New York and New Jersey by ruling that Ellis Island, the point at which millions of immigrants entered the United States, belongs mostly to New Jersey.

More than 40% of all Americans can trace their roots to immigrants who arrived at Ellis Island. Some 16 million people passed through its screening centre.

It's a place with a powerful hold on the American imagination, and New York has always taken its ownership of the island for granted. It's in New York Harbour, overshadowed by the Statue of Liberty, and most people arriving there had their eyes on the skyline of Manhattan and went on to New York, not New Jersey.

So the ruling that New Jersey owns more than four-fifths of Ellis Island comes as a big blow to New York even though it retains the immigration museum there.

The court upheld New Jersey's argument that when the island was expanded with landfill that took it over the state line. New Jersey wanted it because of its development potential.

It already attracts millions of tourists a year, and there's even talk of building a pedestrian bridge across from the New Jersey mainland. New York historians are dismayed - particularly, as they say, arrival on Ellis Island by boat is part of the historical experience.