1845-1849: Irish Potato Famine - Due to a blight on potato crops in the 1840s, many Irish left Ireland for a variety of locations. Many came to the United States, forming the bulk of immigration during this period, a lead-up to the third wave of immigration to the United States. Many of the Irish that came to the United States during this period were agricultural workers, but most settled in cities upon reaching the United States. (1 gen 1845 anni – 1 gen 1849 anni)