There was little Italian emigration to the United States before 1870. However, Italy was now one of the most overcrowded countries in Europe and many began to consider the possibility of leaving Italy to escape low wages and high taxes. Most of these immigrants were from rural communities with very little education. From 1890 to 1900, 655,888 arrived in the United States, of whom two-thirds were men. A survey carried out that most planned to return once they had built up some capital.
Most Italians found unskilled work in America's cities. There were large colonies in New York, Philadelphia, Chicago, Baltimore and Detroit. From 1900 to 1910 over 2,100,00 arrived. Of these, around 40 per cent eventually returned to Italy.
Willing to work long hours on low wages, the Italians now began to rival the Irish for much of the unskilled work available in industrial areas. This sometimes led to hostilities breaking out between the two groups of workers. The Italians were also recruited into the garment industry and by the outbreak of the First World War had replaced the Jews as the main group in the sweated trades.
After the First World War Italians developed a reputation for becoming criminals. This was mainly due to high-profile criminals such as Al Capone, Lucky Luciano, Joe Masseria, Albert Anastasia, Salvadore Marazano, Vito Genovese and Frank Costello. However, a study in Massachusetts revealed that the Italian-born, who comprised 8.0 per cent of the population of the state, made up only 4.2 per cent of those confined in penal institutions. The US Department of Justice also estimates that less than .0025 percent of Italian Americans have anything to do with organized crime.
Italians also became active in trade unions and produced several leaders such as Arthuro Giovannitti and Carlo Tresca. Second-generation Italians became important figures in progressive politics. This included figures such as Fiorello LaGuardia, Vito Marcantonio, and Emmanuel Celler.
In the 1930s a large number of Italians who had opposed the fascist rule of Benito Mussolini arrived in the United States. This included Enrico Fermi, Emilio Segre, Salvador Luria, Arturo Toscanini and Gaetano Salvemini. By the Second World War there were more people of Italian stock living in New York City than in Rome.
The Italian community in the United States were divided over their views on fascism in Italy. However, after the bombing of Pearl Harbor almost all Italians supported the war effort against Benito Mussolini. and Enrico Fermi and Emilio Segre were both involved in the development of the atom bomb.
An investigation carried out in 1978 revealled that since 1820 over 5,294,000 people emigrated to the United States from Italy. This amounted to 10.9 per cent of the total foreign immigration during this period.