Italian immigration in the late nineteenth and early twentieth century relied on a system of both chain and return migration. Chain migration helped Italian men immigrate to such cities as New York in the United States and Buenos Aires in Argentina for work as migrant laborers. Italians generally left Italy due to dire economic conditions and returned wealthy by Italian standards after working in the Americas for a number of years. Italian immigrants were called "ritorni" in Italy and grouped with other Southern and Eastern European migrant laborers under the term “birds of passage” in America. However, after the passage in the United States of the Immigration Act of 1924, return migration was limited and led more Italians to become naturalized citizens. The networks that had been built up by information and money due to chain and return migration provided incentives for Italian permanent migration. Mexican migration to the United States from the 1940s to the 1990s followed some of the same patterns as Italian immigration.