[Tau Food]

You've summed it up perfectly. The baby is an American at birth because his mother is 100% American at the time of the birth.

Just as a apple tree produces only apples, an American mother produces only Americans. You can plant an apple tree (an American mother) in the the middle of an orange grove (foreign soil), but it will continue to produce only apples, never an orange.

Ted Cruz - 2016
(A Natural Born American, by birth and at birth)

[Kansas58]

I agree with you in MOST cases. However, US law does restrict the ability of a minor child to pass citizenship, and US law does require residency, for specific amounts of time, for an adult citizen to transfer citizenship at birth to a child.

[Ray76]

“At” is a point in time.

“By” is causal.

§ 1401 declares who shall be nationals and citizens of United States AT birth. Such persons are citizen at birth BY law.

The causal agent is operation of law. That law may vary causing a person to either be a citizen at birth or not at all.

A person born in country to citizen parent is a citizen BY birth.

The causal agent is birth. This person is always a citizen, this has never been doubted.

[DiogenesLamp]

You've summed it up perfectly. The baby is an American at birth because his mother is 100% American at the time of the birth.

If she's 14 years old, she's still 100% American, but the Baby becomes 100% Mexican. How does that work for ya?

Youse guys have a real funny way of deciding "natural" citizenship.