But it’s more likely we’re witnessing an escalation from random rhetoric to the implementation of concrete restrictions. The shift arguably began with Trump’s travel ban on majority-Muslim countries, but what he is now considering looks like the revival of a discredited policy from the 1920s that left a lasting humanitarian stain on the country. Back then, the US imposed quotas that largely ended immigration from many countries, even as it left the door open to the same groups that Trump now elevates.