From the 14th Amendment:
All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside.
Children born on U.S. soil to parents who are foreign tourists should NOT be given U.S. citizenship! While they meet the “born in the U.S.” condition, they do NOT meet the “subject to the jurisdiction thereof” condition, and they do not “reside” in any State.
We need to put an end to “birthright citizenship”. Just being born on U.S. soil is not sufficient for U.S. citizenship. If both parents are citizens, then yes, that child is a U.S. citizen (a natural born citizen). If both parents are not U.S. citizens, we must look at whether or not the parents and the child are “subject to the jurisdiction thereof” of the United States. In the case of tourists, it is clear they are not. In the case where one parent is a U.S. citizen and the other is not, I think that frequently leads to the scenario of “dual citizen”, where the child is a both a U.S. citizen and a subject/citizen of a foreign country (that of the other parent). Such a child is a citizen, but not a natural born citizen, of the U.S.