I covered the basics in a book I wrote on the early years of the American Mafia. The relevant passages may help to answer your question. They refer to the experience of Italian immigrants in the first half of the 1890s, with a focus on the Morello/Terranova family who were my main subjects. Nothing significant had changed by 1900:

Earlier that day, the ship’s first class passengers, 150 of them, had disembarked at a Manhattan pier. They were presumed to be above the tests and examinations that awaited the eleven hundred more or less impoverished Italians still crammed nervously in steerage. Fourteen months earlier, the US government had opened an enormous immigration centre on the island, staffed by hundreds of inspectors and health officials, and capable of processing as many as 12,000 men, women and children in an hour. There emigrants were questioned as to their employment prospects – men were required to have a job waiting for them – and checked to ensure that they possessed sufficient money to support themselves. They were also tested for a number of diseases. Inspectors carried sticks of chalk and marked people’s coats with codes: L for lame, G for goitre, H for a heart condition. The examination for trachoma, an infectious eye disease, was particularly dreaded; it involved having buttonhooks thrust behind an eyelid. Anyone seen bearing a mark was taken off for more interrogation, and those who were declared unfit to enter the United States were packed off back to their old countries. A few of those who had been marked for questioning dodged this fate by smartly brushing off the chalk upon their clothing...

It was still unusual for families to emigrate together; more than eight Italian immigrants in every 10 were men, and more than half of them eventually returned to Italy. Other than that, thought, there was little in the Ellis Island records to suggest the Terranovas were anything extraordinary. Bernardo gave his age as 43 and said his job was ‘labourer,’ which was normal enough; most Italians were unskilled, and several hundred of his fellow passengers claimed the same menial occupation. He was the only member of the family who could read or write, and that was common, too. The only clue to Terranova’s eminence in Corleone, and to his membership of the Fratuzzi, lies in the notes that the officials made of the Alsatia’s baggage. At a time when the average Italian immigrant entered the country with $6, carrying a single case, the Terranovas mustered 18 pieces of luggage between them. No other family on the ship arrived in the United States with so many personal possessions...

The earliest Italian settlers in New York came from the industrial cities of the north. They were skilled workers and middle class professionals, and they received a cordial welcome. It was not until the 1880s that this pattern changed, and much poorer, less well–educated peasants from the southern provinces began to flood into the city. These Neapolitans and Sicilians were escaping harsh conditions in their homeland: high taxation, an endlessly depressed economy, compulsory military service, and an unprecedented slew of natural disasters – droughts, floods, earthquakes, landslides and volcanic eruptions – that followed one upon the other so relentlessly that they were seen as signs from God.

Unskilled, illiterate and speaking mostly in impenetrable dialect, the men of the south were despised even in Italy, where a bit of doggerel popular at the time perfectly described their position in society:

At the head of everything is God, Lord of Heaven.

After him comes Prince Torlonia, lord of the earth

Then come Prince Torlonia’s armed guards.

Then come Prince Torlonia’s armed guards’ dogs.

Then, nothing at all. Then nothing at all. Then nothing at all. Then come the peasants. And that’s all.

In Manhattan, they were still less welcome. Though useful, insofar as they did dirty jobs that earlier immigrants now thought of as beneath them, Italians from the southern provinces were regarded with hostility by many New Yorkers. Their dark complexions, lack of English and devotion to an alien food were all regarded as distasteful. They were much more volatile than northern Europeans, it was commonly supposed, and prone to deadly knife fights and vendettas. Worse, only a minority embraced American institutions with the fervour expected of immigrants. Few Italians mixed with men of other nationalities, and well under half actually applied for US citizenship. For many Sicilians and Neapolitans, the United States was a place to work hard, spend little, and save ferociously; many planned to return home with their savings, wiring back the collective sum of $30 million a year to relatives and friends. These were habits many Americans regarded as ungrateful and insulting.

Opinion hardened further at about the time the Terranova family first came to Manhattan. There was concern at the number of anarchists and socialists pouring into the country to preach revolution. There was concern at the number of criminals. Nineteen Italians in every 20 of those passing through Ellis Island were found to be carrying weapons, either knives or revolvers, and there was nothing in American law to stop them from taking this arsenal into the city. The Sicilian police were said to be issuing passports to known murderers in order to get them out of the country – a calumny, it transpired, but there were still real reasons to take such problems seriously. So many Italians were passing through Ellis Island every day that it was not possible to check their statements properly. But when the 1,400 passengers on board the SS Belgravia were subjected to a spot investigation, one in six was found to have given false information. “Statistics prove,” the Herald trumpeted in one alarmist feature article, “that the scum of Southern Europe is dumped on the nation’s door in rapacious, conscienceless, lawbreaking hordes.”