That meant, according to Justice David H. Souter's majority opinion, that the subsequent more than 24 acres of landfill, added in stages from the 1890's until 1934, became part of New Jersey -- every inch of that landfill, the Court emphasized in a part of the opinion that probably inflicted the most bitter blow to New York's pride as well as to its hope of salvaging something from a case that had gone badly from the start.

Because the Federal Government actually holds title to Ellis Island, as distinct from the question of state jurisdiction, visitors are unlikely to notice any difference. At issue is the allocation of a relatively small amount of sales tax revenue and, farther down the road, possible development plans.

Gov. Christine Todd Whitman, who was in Washington to attend an unrelated meeting, appeared on the Supreme Court steps several hours after the ruling to declare victory. The decision showed that ''New Jersey's place in history shouldn't be questioned by anybody,'' she said. The Court ruled that Paul R. Verkuil, a law professor whom the Justices had appointed as a special master to conduct a hearing and make a recommendation in the case, had been too generous to New York, even though his 168-page report last year favored New Jersey in most major respects and left New York with a relative crumb.

Mr. Verkuil had concluded that while New Jersey was entitled to the landfill part of the island, the resulting boundary line that ran through three of the historic buildings should be adjusted in the interests of arriving at ''the most practical, convenient, just and fair'' solution.

He proposed that New York be permitted to retain the entire main building as well as a strip of landfill between the building and the ferry slip at which tourists arrive on boats from the Battery in lower Manhattan.