With the vast numbers of German and Irish coming to America, hostility to them erupted. Part of the reason for the opposition was religious. All of the Irish and many of the Germans were Roman Catholic. Part of the opposition was political. Most immigrants living in cities became Democrats because the party focused on the needs of commoners. Part of the opposition occurred because Americans in low-paying jobs were threatened and sometimes replaced by groups willing to work for almost nothing in order to survive. Signs that read "NO IRISH NEED APPLY" sprang up throughout the country.

Ethnic and ANTI-CATHOLIC RIOTING occurred in many northern cities, the largest occurring in Philadelphia in 1844 during a period of economic depression. Protestants, Catholics and local militia fought in the streets. 16 were killed, dozens were injured and over 40 buildings were demolished. "NATIVIST" political parties sprang up almost overnight. The most influential of these parties, the KNOW NOTHINGS, was anti-Catholic and wanted to extend the amount of time it took immigrants to become citizens and voters. They also wanted to prevent foreign-born people from ever holding public office. Economic recovery after the 1844 depression reduced the number of serious confrontations for a time, as the country seemed to be able to use all the labor it could get.

1. Why did the Potato Famine have such a devastating effect on the Irish population?

The Potato Famine had such a devastating effect on the Irish population because the majority of the Irish people were dependent on potatoes as their main food source. When the potato crops were destroyed by a fungal disease commonly known as potato blight, the Irish population faced widespread starvation and disease. Additionally, the British government's inadequate response to the crisis worsened the situation, as they did not provide enough aid to the Irish people, leading to mass emigration of Irish people to other countries, including the United States.