The first wave of immigration to the United States had two main causes. This wave was made up largely of Germans and Irish. These two groups came for different reasons.
For the Germans, a major cause of immigration was political. Germany was in a period of political upheaval in this time. There were many Germans who wanted a more democratic government. Their calls for democracy culminated in an attempted revolution in 1848. Many Germans fled the persecution of dissidents in Germany and came to America.
For the Irish, the major cause of immigration was economic. This was the time of the great potato famine in Ireland. Irish people fled Ireland because it was very hard to find work and the potato famine was making it difficult even to stay alive.