Senator Chris Murphy, the Dem politician from Connecticut, made the following claim on Twitter. "Reminder: "chain migration" is a made up term by the hardline anti-immigration crowd. Its purpose is to dehumanize immigrants. If you're using that word, you're declaring a side."
Is that really so?
Chain migration was not invented by "the hardline anti-immigration crowd". It's widely used within the social sciences and doesn't necessarily even refer to immigration, but to migration from one area to another. For example, the migration of African-Americans from the South to the North in the 20th century has been referred to as chain migration.
Despite Senator Murphy's claim, it's not a derogatory term.
While the origin of the term is tricky to pin down, the widely used definition comes from John and Leatrice MacDonald who defined it in the 60s as movement based on social relationships. The MacDonalds did quite a bit of work involving immigrants. They were not anti-immigration.
The term appears to have been employed at least as far back as the 19th century. It may have been a literal translation of the German, Kettenwanderung.
Either way, Senator Murphy's claim is badly uninformed and wrong. The Senator from Connecticut is launching an attack on a useful and widely used term in academia to score some cheap points on Twitter.