[11][12] Initially, much of the Upper New York Bay's western shore consisted of large tidal flats with vast oyster beds, which were a major source of food for the Lenape.

This was contested in Gibbons v. Ogden, which decided that the regulation of interstate commerce fell under the authority of the federal government, thus influencing competition in the newly developing steam ferry service in New York Harbor.

The island was described as a "hummock along a plain fronting the west side of the Hudson River estuary,"[54] and when the glaciers melted, the water of the Upper New York Bay surrounded the mass.

[72] By the mid-1790s, as a result of the United States' increased military tensions with Britain and France, a U.S. congressional committee drew a map of possible locations for the First System of fortifications to protect major American urban centers such as New York Harbor.

[115]Several prominent architectural firms filed proposals,[112][115][116] and by December, it was announced that Edward Lippincott Tilton and William A. Boring had won the competition.

[103][125][126] Almost immediately, additional projects commenced to improve the main structure, including an entrance canopy, baggage conveyor, and railroad ticket office.

[147][148][149] The immigration station was temporarily closed during World War I in 1917–1919, during which the facilities were used as a jail for suspected enemy combatants, and later as a treatment center for wounded American soldiers.

[166] The committee's report, released in 1934, suggested the construction of a new class-segregated immigration building, recreation center, ferry house, verandas, and doctors/nurses' quarters, as well as the installation of a new seawall around the island.

[165][175] By 1947, shortly after the end of World War II, there were proposals to close Ellis Island due to the massive expenses needed for the upkeep of a relatively small detention center.

[179][178] Ellis Island closed on November 12, 1954, with the departure of its last detainee, Norwegian merchant seaman Arne Pettersen, who had been arrested for overstaying his shore leave.

[185] In 1959, real estate developer Sol Atlas unsuccessfully bid for the island, with plans to turn it into a $55 million resort with a hotel, marina, music shell, tennis courts, swimming pools, and skating rinks.

[205] In 1970, a squatters' club called the National Economic Growth and Reconstruction Organization (NEGRO) started refurbishing buildings as part of a plan to turn the island into an addiction rehabilitation center,[207] but were evicted after less than two weeks.

[231] The north side was temporarily closed after being damaged in Hurricane Sandy in October 2012,[232] though the island and part of the museum reopened exactly a year later, after major renovations.

[241] The current complex was designed by Edward Lippincott Tilton and William A. Boring, who performed the commission under the direction of the Supervising Architect for the U.S. Treasury, James Knox Taylor.

[247] The south elevation of the first floor contains the current immigration museum's main entrance, approached by a slightly sloped passageway covered by a glass canopy.

[242][142] When the room's roof collapsed during the Black Tom explosion of 1916, the current Guastavino-tiled arched ceiling was installed, and the asphalt floor was replaced with red Ludowici tile.

[224] The powerhouse is no longer operational; instead, the island receives power from 13,200-volt cables that lead from a Public Service Electric & Gas substation in Liberty State Park.

[276][271] It housed 25 to 30 beds and was intended for the temporary treatment of immigrants suspected of being insane or having mental disorders, pending their deportation, hospitalization, or commitment to sanatoria.

All structures were designed by James Knox Taylor in the Italian Renaissance style and are distinguished by red-tiled Ludowici hip roofs, roughcast walls of stucco, and ornamentation of brick and limestone.

[317][306] Beginning in the 1890s, initial medical inspections were conducted by steamship companies at the European ports of embarkation; further examinations and vaccinations occurred on board ship during the voyage to New York.

[161][162][163] Uniformed military surgeons staffed the medical division, which was active in the hospital wards, the Battery's Barge Office, and Ellis Island's Main Building.

[343] After the American entry into World War I, about 1,100 German and Austrian naval officers and crewmen in the Ports of New York and New London were seized and held in Ellis Island's baggage and dormitory building.

[348] During and immediately following World War II, Ellis Island was used to hold German merchant mariners and "enemy aliens"—Axis nationals detained for fear of spying, sabotage, and other fifth column activity.

Two notable communists known to have been imprisoned on Ellis Island include Billy Strachan, a pioneer of black civil rights in Britain, and Ferdinand Smith who co-founded the first desegregated union in the history of the United States.

Henry Fairfield Osborn's opening words to the New York Evening Journal in 1911 were, "As a biologist as well as a patriot...," on the subject on advocating for tighter inspections of immigrants of the United States.

[334][328] There were three types of illness that were screened for: The people with moral or mental disability, who were of higher concern to officials and under the law, were required to be excluded from entry to the United States.

[371][372] The myth of name changes at Ellis Island still persists, likely because of the perception of the immigration center as a formidable port of arrival,[371] and because it is used in popular books and movies such as The Godfather Part II.

[379] The third floor contains a dormitory room, Restoring a Landmark, Silent Voices, Treasures from Home, and Ellis Island Chronicles, as well as rotating exhibits.

[383][384][261] The Wall of Honor outside the main building contains a list of 775,000 names inscribed on 770 panels, including slaves, Native Americans, and immigrants that were not processed on the island.

[223] The NPS held a competition for proposals to redevelop the south side in 1981 and ultimately selected a plan for a conference center and a 250-to-300-room Sheraton hotel on the site of the hospital.