Donald Trump 2016 RNC speech (By Voice of America via Wikimedia Commons ) Immigration has always been a thorny issue in American society. Demographic changes have oftentimes resulted in the emergence of nativist movements opposed to the arrival of new people who were deemed dangerous and "unassimilable". In 1840 the US population was a little over 17 million. The largest city, New York, had but 312,000 people. In that decade, however, a new wave of immigration, mainly from Ireland and Germany, led to a rapid increase in the US population, which by 1860 had reached 31.4 million. Those immigrants, despite being white and Christian, were often met with suspicion and hostility. An anti-immigrant movement arose among native-born English-speaking protestants, who viewed the newcomers as a threat to the identity and the political system of the country. Associations spreading xenophobic ideas were formed, the most influential of which was the Know-Nothing Party .