There was no food which caused the Irish Potato Famine.
We're running low on crops.
There were religious restrictions on the Irish. Being Catholic in Ireland is much more a heritage than a belief. Also, during the immigration, they used ships to travel.
You are not catholic. What a disgrace, you cannot come on the ship. Stay here.
The Irish had a really hard time getting jobs since they were poor. The jobs most Irish people would get is being a servant (females) and building things (men) such as railroads and canals.
Employee needed, NO IRISH!
The Irish settled in Boston, New York City, Baltimore and Philadelphia. Their lives did not really get better because they were still treated differently and were left out a lot due to their religion.
Unfortunately, life for the Irish turned out being the same. They were not treated any differently in the U.S since most of them were catholic. The jobs there were dangerous and were very low-paying jobs, the discrimination was just growing stronger and it was harder for them to feel comfortable since they were new and nobody seemed to even care about them.