American immigration history is chock full of policies and restrictions, and you can see the effects in the distribution of immigrants into this country over the years. Alvin Chang for Vox steps you through the major policy shifts since 1820.
The graphic above shows how these policies affect who enters the country. It shows 200 years of legal immigration into the United States — and how different policies and international dynamics affect the patterns of who gets let in. Migration into the United States has ebbed and flowed in tandem with who policymakers believe ought to be allowed refuge and who doesn't qualify.