Why is Ellis Island divided between New York and New Jersey? The strange border hidden inside America's most famous immigration station

Ellis Island belongs to two states because most of the island visible today did not exist when New York and New Jersey agreed on their boundary. Their 1834 compact left the original island under New York's jurisdiction. The federal government later enlarged it with landfill to accommodate the immigration station.

In 1998, the Supreme Court ruled that most of this added land lay in New Jersey. The island remained federally owned and operated as one national monument; the judgment settled state jurisdiction rather than dividing ownership of the historic site.

How New York and New Jersey Came to Share a Harbor

The harbor soon became one of the most important commercial locations in North America. Its protected waters, connection to the Hudson River and access to the Atlantic Ocean encouraged the development of maritime trade. New York grew into a major colonial port, while settlements on the New Jersey shore participated in the same regional economy. However, the geographical and legal relationship between the two sides of the harbor was never entirely straightforward. The Hudson River, Upper New York Bay and surrounding islands formed a complex system of waterways that could be interpreted differently when defining political boundaries.

New York claimed extensive authority over navigation, commerce and certain islands within the harbor. New Jersey, meanwhile, maintained that its territorial rights extended into the waters separating it from Manhattan and the other islands under New York's administration. These competing claims became increasingly important after American independence. Both colonies became states within the United States, but their shared maritime geography continued to create disagreements over taxation, jurisdiction, transportation and economic regulation. The rapid commercial expansion of New York Harbor during the early nineteenth century made the absence of a completely settled boundary particularly problematic. Shipping companies, dock operators and local governments needed to know which state possessed authority over particular waters and waterfront locations.

The Agreement of 1834 and the Original Ellis Island

In 1833, representatives of New York and New Jersey negotiated a compact intended to resolve their longstanding boundary disputes. The agreement was approved by the two state legislatures and received congressional consent in 1834, giving it binding legal force. The compact established the principal interstate boundary through the Hudson River and New York Harbor. In general, the line followed the middle of the relevant waterways, placing the waters closer to the New Jersey shore within New Jersey's territorial sphere. However, the agreement included important exceptions concerning particular islands. Ellis Island and Bedloe's Island, later renamed Liberty Island, were recognized as remaining under New York's jurisdiction, even though they lay on the New Jersey side of the principal harbor boundary.

At the time, Ellis Island was very small. Its natural land area measured only about three acres, or approximately 1.2 hectares. It was considerably smaller than the island familiar to modern visitors. The island had previously been associated with private ownership and various military uses. New York had transferred its interest in the island to the federal government in 1808, and federal authorities subsequently used it for defensive and military purposes, including the storage of gunpowder.

How Immigration Turned a Small Island into a Much Larger One

The federal government gradually assumed greater responsibility for immigration administration. By the late nineteenth century, officials needed a large facility capable of processing thousands of arriving passengers while maintaining medical inspections, administrative records and detention accommodations. Ellis Island was selected as the location for a major federal immigration station. Its position within New York Harbor made it accessible to arriving ships while allowing immigration authorities to process passengers away from the crowded streets of Manhattan. The station officially opened on 1 January 1892. Annie Moore, a teenage immigrant from Ireland, is traditionally recognized as the first person processed through the new facility.

However, the natural island was far too small to accommodate the infrastructure required for a major immigration center. The federal government therefore began expanding it through land reclamation, depositing fill material into the surrounding waters. This process continued over several decades. Sand, soil, rock and other material were used to create new ground around the original island. The expanded territory allowed the construction of larger buildings, hospital facilities, administrative structures and supporting infrastructure. A fire destroyed the original immigration buildings in 1897. A new main immigration building opened in 1900, and further expansion continued as the volume and complexity of immigration administration increased.

Eventually, the island grew from approximately three acres to around 27.5 acres. In other words, most of the land visible today did not exist when New York and New Jersey signed their boundary agreement in 1834. For much of the twentieth century, that question remained unresolved.

Why the New Land Created a Border Dispute

Under the 1834 compact, New York retained jurisdiction over Ellis Island as it existed at that time. New Jersey, however, possessed underlying sovereign rights over much of the submerged land surrounding the original island on its side of the harbor boundary. When the federal government expanded Ellis Island, it deposited material onto submerged territory that had previously belonged within New Jersey's geographical jurisdiction.

New York maintained that the expanded island should remain under its authority. From this perspective, the new land was simply an enlargement of an existing island that the compact had expressly assigned to New York. New Jersey adopted a different interpretation. It argued that the compact protected New York's jurisdiction over the original island but did not transfer sovereignty over surrounding underwater territory. Constructing new land on that territory could not automatically extend New York's jurisdiction.

This disagreement involved a traditional principle of boundary law. When natural processes gradually alter a shoreline, territorial boundaries may sometimes change with the land. However, sudden changes or deliberate alterations do not necessarily have the same legal effect. Artificial land reclamation was therefore fundamentally different from the slow natural accumulation of sediment. The federal government had physically expanded Ellis Island, but that did not necessarily mean that the legal boundary had expanded with it. Because the reclaimed territory represented most of Ellis Island's total area, the dispute concerned the jurisdictional status of the great majority of the modern island.

From an Immigration Station to a Supreme Court Case

Ellis Island operated as a federal immigration station until 1954. During its history, more than twelve million immigrants passed through its facilities, making it one of the most important sites in the development of modern American society. Changes in immigration law gradually reduced the island's role. By the middle of the twentieth century, its original function had largely disappeared, and the federal government closed the station. The island subsequently entered a period of uncertainty. Many buildings deteriorated, and discussions emerged over how the historic site should be preserved. In 1965, Ellis Island became part of the Statue of Liberty National Monument, placing it under the administration of the National Park Service. Large-scale restoration followed during the 1980s, and the main immigration building reopened to visitors in 1990 as a museum.

In 1993, New Jersey initiated a legal action against New York before the United States Supreme Court. Under the Constitution, the Supreme Court possesses original jurisdiction over disputes between states, allowing it to hear certain territorial cases directly rather than only through the usual appeals process. The proceedings required extensive historical and geographical investigation. Lawyers and specialists examined the 1834 compact, nineteenth-century surveys, old harbor maps, the history of land reclamation and the precise extent of the island before its enlargement.

The Supreme Court Decision of 1998

On 26 May 1998, the United States Supreme Court delivered its decision in New Jersey v. New York. By a vote of six to three, the Court ruled that New Jersey possessed sovereign authority over the land added to Ellis Island after the 1834 agreement. The majority concluded that the compact had preserved New York's jurisdiction over the island as it existed at the time of the agreement. It had not granted New York sovereignty over additional territory that might later be created by artificial filling. The Court distinguished the original island from the surrounding submerged land. Because much of the new land had been constructed within territory subject to New Jersey's underlying sovereignty, it remained within New Jersey's jurisdiction.

New York retained the original island, including the site of the principal immigration building. New Jersey received jurisdiction over most of the surrounding reclaimed land, including substantial parts of the hospital and other facilities. The Court did not accept the argument that practical convenience alone justified placing the entire island within New York. The location of the legal boundary depended on the historical compact and the applicable principles of boundary law.

A final decree entered in 1999 formally established the interstate boundary on the island, using detailed surveying information to identify the relevant areas. The decision did not transfer ownership of the historic site away from the federal government. Ellis Island continued to be federally owned and administered by the National Park Service. The ruling concerned the territorial jurisdiction of the two states rather than the federal government's right to operate the national monument.

Why Ellis Island's Border Is So Unusual

The boundary is not marked by an international-style frontier. There are no passport inspections or immigration checkpoints between the two states, and visitors ordinarily experience Ellis Island as a single historical site. Nevertheless, the line has legal significance. It determines the geographical jurisdiction of New York and New Jersey over their respective portions of the island, even though federal authority governs the monument's principal operations.

The arrangement also creates a striking distinction between Ellis Island and nearby Liberty Island. Liberty Island, home to the Statue of Liberty, remains entirely within New York's jurisdiction under the historical compact. Ellis Island, by contrast, acquired its unusual division because most of its current territory was created artificially after the compact had been signed.