A gorgeous visualization of 200 years of immigration to the US - Vox: Bronshtein pulled 200 years of government data to put together the visualization. There's an interactive version on her website: you can hover over any color, at any point, and see the exact number of immigrants who became residents from that country in that decade.
But taken as a whole, the chart tells a very clear story: there are two laws that totally transformed immigration to the United States.