The Ellis Island Immigrant Facility was the main entry point immigrants had to pass through, from January 1, 1892, until November 12, 1954, in order to enter the United States. It was here that all transatlantic immigrants were inspected, processed, and sometimes held in quarantine About 2% of immigrants were not allowed entry to the United States, and were returned to their home country, earning Ellis Island the nicknames The Island of Tears and Heartbreak Island.

Ellis Island is situated at the mouth of the Hudson River, in New York Harbor, between Jersey City, New Jersey, and New York City, New York. It was originally called Little Oyster Island, and was later named after the man who first owned it, Samuel Ellis.

Prior to 1891, the Castle Garden Immigration Depot in Manhattan was used to process immigrants entering the United States.

Immigrants disembarking onto Ellis Island were viewed by doctors; those who were visibly sick or had obvious medical needs had symbols marked on their clothing in chalk. For example, if a woman was obviously pregnant, the letter PG would be chalked on her clothing; the letter C signified conjunctivitis; an X meant the immigrant was suspected of having mental illness; a circled X meant the immigrant displayed definite symptoms of mental illness.

Some managed to enter the country by turning their clothing inside out or slyly wiping the marks off. For healthy immigrants it generally took from two to five hours to be processed before being admitted into the United States.

For those less fortunate, those who appeared to be ill in either mind or body, the process could take days in the facility hospital. Many of the sick died in the hospital. Immigrants with contagious disease, insanity, or criminal background were rejected; so, too, were those unable to work or without any viable skills.

Some of the buildings on Ellis Island were damaged during World War I, but the facility was still used to intern some enemies, as well as process returning injured or sick U.S. soldiers.

The year 1907 was a busy one for the facility: more than a million immigrants were processed. Mid-April of that year saw a day where nearly 12,000 immigrants were processed. But after the Immigration Act of 1924, which restricted immigration and also allowed processing at embassies over seas, Ellis Island became mainly a detention and deportation processing facility.

Today, Ellis Island is a national landmark and historic site and houses a museum.