I have always thought of myself as an American citizen. I was born in New Jersey (which, jokes aside, does count) and have a birth certificate that proves it. But suppose birthright citizenship were to go away? It wouldn’t be enough to prove I was born here: I’d need in addition to prove that one or both of my parents were citizens, or at least legal residents. (The latter seems enough to satisfy the usual argument about the meaning of “subject to the jurisdiction thereof”, but since this wouldn’t be settled law, who knows?)
My father was also born in this country, but again that’s insufficient. His parents were both from London, and if they ever applied for citizenship, I’ve never seen the paperwork. In fact, neither of their names appears on the Ellis Island website, and there are some hints that they emigrated to Canada first (within the Empire) and later entered the US in not entirely kosher fashion. My mother was likewise native-born. Her side has been here longer, but that only makes things murkier, as it would be harder to find an ancestor with an uncontested legal right to live in the US. Though it’s a bit discomfiting, I have to face the fact that I might, at this late date, become a stateless person.
Fortunately, the rest of the family is not in the same (metaphorical, or, if a country could be found to take me, perhaps literal) boat. My wife, who immigrated here in her twenties, has an official government document issued on the day she became a citizen, and presumably her unquestioned legal status would suffice for the children despite my shaky one. In fact, what might well save me would be a compassionate visa issued to keep the family together. But all of you who are native-born five generations back, well, you’d better find an immigrant to marry (or adopt) you, and damned quick.