Final answer:
The great famine of the 1840s led to two million Irish emigrating to the United States, primarily drawn by job opportunities.
Step-by-step explanation:
During the great famine of the 1840s in Ireland, approximately two million Irish people were pushed from Ireland and pulled to the United States by the prospect of jobs. The Irish Famine, a result of blight destroying the potato crops, led to mass starvation and wide-scale emigration. The population of Ireland saw a significant decline from over 8 million in the 1800s to about 4.7 million today. In the United States, Irish immigrants faced substantial challenges, including discrimination, but they were drawn by the employment opportunities and the hope of a better life.