As with North America and the lure of its western frontier, it was largely down to land, resources and opportunity, coupled with Old World troubles. The whole of South America in 1850 contained fewer than 18 million people, against over 430 million today, though as in North America many migrants made it no further than their port of arrival, contributing to rapid urban growth rather than interior settlement.

The movement was a response in part to agrarian problems in Europe (with 260 million inhabitants by 1850) where crisis in the 1840s and slowing demand for arable produce exacerbated rural underemployment (exacerbated ironically by imports from the new lands of the Americas along with Russia): agricultural population was already in decline in many countries from the century's third quarter, and Atlantic shipments of grain and later meat contributed to a general drop in farm prices from the 1870s exceeding even the general deflation of the 1873-96 "great depression" (in fact a succession of falls punctuated by hesitant recoveries).

As with anglophone movement to the US and Canada, South America held obvious linguistic appeal to Iberian migrants, but as with Irish movement to New York or Boston, the presence of existing populations of recent migrants also exerted a significant attraction: Enrico Moretti (Social networks and migrations, International Migration Review 33:3, 1999) suggests that it was this availability of ready social networks that offered a pole to increased Italian numbers from the 1880s, culminating in the mass movement of 1901-13.