"So, anyhow, we had to get off of the ship and we were put on a tender, which took us across to Ellis Island. And when I saw Ellis Island - it's a great, big place - I wondered what we were going to do in there. And we all had to get out of the tender, and then into this, and gather your bags in there, and the place was crowded with people, and talking, and crying - people were crying. And we passed, go through some of the halls there, and tried to remember that the halls, big halls, big open spaces there, and there was bars, and there was people behind these bars, and they were talking different languages, and I was scared to death. I thought I was in jail." (Mary Mullins, an Irish immigrant)

By the middle of the 19th century, New York City's population surpassed the unfathomable number of one million people, despite its obvious lack of space. This was mostly due to the fact that so many immigrants heading to America naturally landed in New York Harbor, well before the federal government set up an official immigration system on Ellis Island.

At first, the city itself set up its own immigration registration center in Castle Garden near the site of the original Fort Amsterdam, and naturally many of these immigrants, who were arriving with little more than the clothes on their back, didn't travel far and thus remained in New York. Of course, the addition of so many immigrants and others with less money put strains on the quality of life. Between 1862 and 1872, the number of tenements had risen from 12,000 to 20,000 and the number of tenement residents grew from 380,000 to 600,000. One notorious tenement on the East River, Gotham Court, housed 700 people on a 20-by-200-foot lot.