The Irish, or Great, Famine (1845–51) was the cause for the increase in Irish emigration (leaving one country to settle in another) to the United States. In 1845 blight, a plant disease caused by fungus, attacked the potato plants of Ireland. Because the potato was the main source of food for the Irish, thousands of people were forced to go without food. As a result of the blight, farmers lost their farms and people began to die from starvation and disease. As the famine continued, millions of Irish emigrated to the United States with the hope of a better life. It is estimated that by the time the Irish Famine had ended in 1851, 1,000,000 people had died from starvation and another 700,000 to 1,000,000 people had emigrated to the United States.
Further Information: Nardo, Don. The Irish Potato Famine. San Diego: Lucent, 1990; Oxford Encyclopedia of World History. New York: Oxford University Press, 1998.