How did patterns of immigration to the united states change between the 1840s and the 1910s?

The 1910s marked the highest point of Italian immigration to the United States. During the time around the 1840s most immigrants that came to the US were from Germany and Ireland (Western Europe) and after about 1870 the tide shifted and a flood of immigrants from Eastern Europe (Russia, Poland, Italy, etc.) and Asia came into the US. Also the Chinese immigration dropped precipitously after the Chinese Exclusion Act of the 1880s. They worked on railroads, raised agricultural production, machinists, carpenters, sailors, and took any job they could find. They were paid less than what was usually paid, worked for less.