Arable land is both scarce and scattered in southern Italy, leading to many isolated settlements — contributing in turn to the linguistic and other cultural differences. Moreover, there are very few long navigable rivers to facilitate trade and communication. Such modern means of travel or communication as broadcasting, railroads, and airlines were of course not yet in existence, or were not yet significant in southern Italy, when the massive immigration to America was taking place. Even in the middle of the twentieth century, however, geographical isolation was still extreme in some southern Italians villages.
The climate and terrain of southern Italy contributed to its poverty. While the temperatures are relatively mild, rainfall is both low and concentrated in only a few months. The growing season is dry — "drought may endure for six months or more." When the rains finally come, they are torrential, causing erosion. The dryness during the growing season in turn limits the use of fertilizers. The impermeability of much of the hilly soil facilitates rapid water runoff when it does rain, and the deforestation of southern Italy's once heavily wooded areas adds to both erosion and the collection of water in stagnant pools, breeding malaria. Italy has been the most malarial country in Europe, and southern Italy more so than the rest of the country. In addition to the direct suffering and death caused by malaria, disease also exacted an economic toll. Because the most fertile lowlands were also the most malarial, peasants and agricultural workers lived up on hillsides in order to be away from the malaria-bearing mosquitoes at night, when they bite. This in turn meant that much of the day was spent going to and from home and work — often miles apart — instead of actually working.
While much of southern Italy is hilly and mountainous, the highlands are at just the wrong height for agricultural purposes. They are too high and rugged to be good cropland and too low to collect snow, which would melt and give a slow, steady runoff of water during the spring. In addition to lacking these advantages common in some other European countries, Italy also does not have its sod broken up by nature through successive freezes and thaws during the winter. The southern Italian farmer must perform the vital function of breaking up the soil entirely by his own efforts and that of his animals pulling the plow.
Italy's natural deficiencies are both agricultural and industrial. About three quarters of the land area of Italy consists of mountains and hills. Only about half of the land is arable, and most of that is in northern Italy. In the south, the mountains "reach so close to the sea that arable land is limited to mountain villages, high plateaus, or coastal plains" — the latter being generally "very narrow." Italy is also lacking in both the quantity and quality of coal and iron ore needed for producing iron and steel — a mainstay of modern industry.
History has added to the problems created by nature. Southern Italy was long a battleground for contending empires and dynasties, which fought back and forth across the Italian peninsula for centuries, going back at least as far as the Roman Empire. For two centuries during the Middle Ages, invasions were "frequent and almost annual." At various times, southern Italy was conquered by a variety of foreigners, including the Lombards, the Arabs, and the Normans. Massacres, pillage, rape, and enslavement were the common fate of the population.
Northern Italy has been better treated by both nature and man. The rain falls in the spring and summer, when it is needed for agriculture. It has "several rivers, whose waters are kept at a relatively steady level by melting Alpine snows," and those "provide considerable water and power for agriculture and industry." In addition, northern Italy has "a system of irrigation that has been nowhere excelled and rarely approached" — at least during the era of massive immigration to America. Northern Italian agriculture has been described as "luxuriant under cultivation," yielding "a notable variety of crops." Deforestation and other natural and man-made evils of the south were less prevalent in the north.
Thomas Sowell. Ethnic America: A History. New York: Basic Books, 1981.